Flavours of Forums Forever
- Sep 9, 2013
It was something they were saying well over a decade ago but certainly since 2018 they have consistently said as long as they can extract the content, HTML validity does not matter.They have stated many times the exact opposite of your claims: they do not use any HTML standards including W3C validation as a ranking factor.
Other search engines may vary. That said, good HTML is just good for everyone.