I kinda feel for the rest.
Marseille and Monaco built competitive teams relative to the league, Nice, Lyon and Lille aren't far behind, midtable clubs like Strasburg, Rennes, Brest has decent players. They are behind the top 4 leagues for sure, but take out PSG and the table looks good.
Obviously a lot of people don't know their players, but sides like Marseille, Monaco, Lille, Lyon, Rennes, Brest always seemed like solid, respectable teams.
I think people just believe they're rubbish because they see Ligue 1 as a 'tinpot' league as you put it, and because of PSG's financial dominance they assume everyone else sucks.
You can definitely imagine teams like Lille and Lyon getting midtable in the PL if they perform well. But a lot of people would scoff at that and consider teams like that Championship level or relegation candidates at best.
I don't think it's fair, they are decent teams. They're definitely better than sides like Southampton and Ipswich and Leicester. The league just has little hype and is not watched by a lot of fans. Most fans invest all their watching in the PL.