This is nonsense. N'Jie and Nkoudou didn't fail because of a lack of physicality or intensity, they just weren't good enough for a team at the top end of the PL, they weren't good enough for teams at the top of Ligue 1 either. They were young punts that didn't pan out like Clarke or Rodon.
By your logic we've learned from Kante that that Ligue1 is vastly superior to the PL because he never managed to win Ligue1 but pissed the PL twice. He's also able to play with more intensity and physicality than most PL players.
Did we learn from signing people like Sissoko and Doherty from the PL that the PL is shit?
There are plenty of players from Ligue1 (and other leagues) who have been great allover Europe, including in (and winning) the PL.
Kulesevski was failing at Juve in Serie A, yet found it piss easy to score and assist in the PL. What have we learned from this, that Serie A is tougher than the PL?
Your theory is nonsense. It's just about finding the right players. Wherever you are looking, and Ligue 1 doesn't lack physicality or intensity - it just lacks finesse, because it all gets exported pretty quickly to the rest of Europe.
PSG manager Mauricio Pochettino made one notable comparison between Ligue 1 and England's top flight in the Premier League.
psgtalk.com