Two famous 18th-century teachers of the style were Antonio Bernacchi (1685–1756) and Nicola Porpora (1686–1768), but many others existed. A number of these teachers were castrati. Singer/author John Potter declares in his book Tenor: History of a Voice that:

"For much of the 18th century castrati defined the art of singing; it was the loss of their irrecoverable skills that in time created the myth of bel canto , a way of singing and conceptualizing singing that was entirely different from anything that the world had heard before or would hear again."

One reason for the eclipse of the old Italian singing model was the growing influence within the music world of bel canto's detractors, who considered it to be outmoded and condemned it as vocalization devoid of content. To others, however, bel canto became the vanished art of elegant, refined, sweet-toned musical utterance. Rossini lamented in a conversation that took place in Paris in 1858 that: "Alas for us, we have lost our bel canto".

Franz Sieber wrote: "In our time, when the most offensive shrieking under the extenuating device of 'dramatic singing' has spread everywhere, when the ignorant masses appear much more interested in how loud rather than how beautiful the singing is, a collection of songs will perhaps be welcome which – as the title purports – may assist in restoring bel canto to its rightful place."