Getting back to the idea that the greatest boxing has to be a heavyweight.
To reinforce this concept, lets apply weight division to some other sports.
Take the shot-put. Say we had weight divisions in that event. Would anyone dare to say that 10st welterweight thrower is greater than a heavyweight thrower who could throw 10m further than him?
No, that would be silly.
Same thing applies to boxing.
And, of course, if a lighter-weight division boxer moves up in weight and gets defeated it does reflect on their success at the lower weight.
For example, would anybody reading this thread dream of calling Ezzard Charles the greatest boxer of all time? No, that would be silly because we know that he got flattened by Jersey Joe and Rocky Marciano.
But, wait a minute, don't a lot of polls list Ezzard as the greatest light-heavyweight ever?
Well, yes they do, and Ezzard sorted out the great Archie Moore at least twice!
But, But, BUT! those defeats at heavyweight mark him down!
Or, put another way, his "greatness" was diminished by his defeats at the higher weight.
And, if Ray Robinson had tackled Floyd Paterson( who wouldn't appear in any top 10 heavyweight lists) and been flattened, his reputation would have been seriously diminished.