Do grids on float not true?

Question

Layout

Hello. I heard an opinion from a fairly experienced specialist (leads popular layout courses) that making grids on floats is not very good. They say they are only for wrapping the text, that's why you use them. And for grids, flexes + grids.
How true is this statement? It seems to me that floats:
1. Cope with building grids
2. Always work as expected
3. Better supported
Should I switch to flex?
Thank you.

Answer 1

And what did this popular specialist do while there were no flexes and grids, did he make up tables?
If the tool copes with its task, why blame it for something?

Answer 2

Should I switch to flex?

if there are no browsers in the TK that do not support them - it’s worth it
. An experienced specialist should have a couple of years of layout on tables - if there are none, then he is not a specialist