You are entitled to your strong opinions, but to make such sweeping pronouncements with such limited understanding only leaves egg on your face. Sometimes it's better to ask why rather than to condemn or dismiss.

The ABC isn't badly screwed up; rather, Barfly is terribly limited in what it can interpret, particularly in terms of ABC 1.7 and 2.0 extensions. Use the folkinfo.org converter instead--it produces cleaner scores anyway. What I do is not "non-standard"--quite the reverse. I mentioned the use of the extensions in the main thread. You do not need to see the original notation to make sense of what I've written, you need only to read the newer ABC standards.

The Barfly solutions to multiple voices are highly proprietary, and don't address some of the needed functions well or at all. You're welcome to create your own Barfly-specific versions, but when it comes to multiple-voiced music (apart from simple chordal alignment) there sadly IS no solution that works across all or most converters. Adhering to the standard and using a maximally standard-compliant converter accessible to everyone (like the folkinfo converter) is the most one can do.

I use P only for tune division. The divisions I typically use correspond to (1) modern notation (combined), (2) sometimes, the refrain separately, (3) each part of the original notation, to be played serially rather than in combination, since they rarely align properly due to original notation timing errors or idiosyncratic interpretation (for instance, a half note or whole note isn't always of standard duration). The primary intent of my P-directive usage is to be able to repeat or silence these various sections by simply altering the P directive in the header. I also found that using P directives helped to isolate the staves, to inhibit undesired cross-score polution (such as anticipatory clef changes and cancelling accidentals). I never separate individual voices with P-directives when they're combined in the modern notation.

The converters (including the folkinfo one) sometimes get confused when parts need to be tacet, such as when I want to get individual voices to be played serially after the ensemble rendition. A directive like "%%score 2" ought (in my interpretation) to suffice to silence all other voices during that section, but the MIDI generators tend to ignore scoring as irrelevant--actually, the behavior is stranger than that. I can think of only three solutions: (1) include all parts throughout, with explicit rests for all parts but the one that plays--this bloats ABCs terribly and unnecessarily; (2) create separate ABCs (X-numbered sections, each with its own header)--this makes it difficult to combine the group of related sections into a single PDF or MIDI file, particularly if the master ABC file contains multiple songs; (3) use only one voice throughout the solo section, changing clef/range as desired. The last is the option I have resorted to in many cases, but if there are only two voices, that hasn't always been necessary; for some reason the %%score/voice changes then seem to work as expected.

Another glitch you'll sometimes notice when listening to the original notation stuff is that some accidentals are not sticky enough. That's because ABC only offers two options (via three %%propagate-accidentals modes) to control how long the effect of an accidental persists: an accidental applies either only to the current note or until the end of the bar. But in the old scores, persistence was somewhere in between, since bar lines were used to demarcate sections rather than to indicate measures. This creates a quandary, because I can be faithful either to the score or to the ear, but not to both. Sometimes I added explicit accidentals to each affected note, identifying through a footnote which accidentals were not really notated explicitly in the score, but at other times I just left the MIDI to be wonky (since the important part is really to emulate the original presentation), and at other times I just suppressed MIDI playback for the original notation entirely. If ABC supported the concept of invisible bar lines, I could have used them to achieve the desired effect.

The problem goes deeper, since the original notation indicated accidentals either by a flat signs before a note or an X above or below the note--occasionally, the now familiar sharp sign was used--different scribes, different conventions. The flat or sharp was also used to naturalize a note; the natural had not yet evolved as a separate symbol. I could only get the desired MIDI note by the use of sharps or naturals, per modern conventions. Sometimes I indicated both sharps and X's, but particularly in the latter scores, I just use modern convention. The problem still niggles me, but not enough to do what I "should" have done: produce separate ABCs for the presentation (PDF score) and for the sound (MIDI). I've been trying to keep things simple, with only one relatively short, uncluttered ABC for the whole shebang.

The quite earthly point of making PDF and MIDI files available in addition to the ABC they're generated from is that, no matter how often or as clearly as we explain it, most readers here haven't an earthly idea of what to do with ABC notation--it just looks like gobblety-gook. Further, as noted above, ABC converters are annoyingly inconsistent when it comes to the handling of anything but simple one-voice MIDIs (i.e. extensions beyond v1.0 or v1.2). Having the PDFs and MIDIs allows people to hear/view the songs most directly, without any learning curve, intermediate generation steps or worries about what their chosen generator will or will not handle. It's only if they wish to transpose scores, alter the tune or score, or export the notation that they need recourse to the ABC. (Note that there are many tools that can transpose and change the tempo of MIDI playback.) Also, eventually I'd like to put the MIDIs in a permanent repository that supports live linking, so that we can add direct links in the song index and ABC posts, and with one click people can listen to the music, as with the natively-hosted Mudcat and DigiTrad MIDIs.