I’ve been playing the French for 20 years. When I started I was a USCF C Class player. I’ve been USCF A Class since just before I turned 50. I’m in my 60s.
I’ve beaten quite a few titled players with the French. Of course, I’ve lost many games with it as well.
Several world champs were fond of the french defense , it cant be bad ...
Botvinnik and Petrosian played the French more often than any other opening. Korchnoi, Uhlmann, Byrne and Maroczy were prominent players who played the French a lot.