I think it is more likely to be the dynamic range of early Microphones that caused the problem,and led to the crooning style, rather than the frequency range.
Even a Carbon Mic has a frequency range between 100Hz and 10kHz- and (almost) nobody can sing at 10K!
Similarly, if a valve (tube in USA english) can handle radio frequencies, it's not going to blow with even the highest audio notes.
On the other hand, early ribbon mics had a very narrow range of sound pressure levels. A Bel Canto singer sings very quietly, and very loud- and being used to unamplified performances, will never have heard of mic technique.
A crooner has a much more limited dynamic range- and microphone technique is evident at a very early stage in recordings.
Cheers
Dave