you're probably expecting some major disagreement from me, but you are criticizing technical trends which arouse out of the fach system, not the fach system itself. with that in mind, your criticism is valid. several examples I think of are:I would caution against the assumption that nineteenth century singers were normally equally competent in the entire repertoire they sang. Certainly, there were lighter and heavier voices, just as now, and the major difference was that in those pre-Wagner, pre-verismo days, thorough bel canto schooling was expected of all front-rank singers; specialization hadn't yet divided singers into the "fachs" some of us are so fond of distinguishing.
1) failure to teach heavier voices to sing some degree of coloratura. among healthily-produced big voices, everyone from Kirsten Flagstad to Dolora Zajick to Tito Gobbi believes that vocal flexibility is important in keeping the voice fresh.
2) teaching lighter voices that they don't need to support the bottom 2/3 of their range (except for tenors, in which case it's all types of tenors and the bottom 4/5 of the range lmao).
3) (especially in Wagner), the notion that big voices do not need to sing with legato (hell, we basically expect lyric singers to sing legato anymore. after dramatic voices, some of the biggest offenders are those girly lil coloraturas, and it seems like we've given up on the concept of male voices singing legato altogether apart from Hvorostovsky).