He's right for the wrong reasons.
Sport jiu-jitsu has become far more specified. A lot of it has almost no applicability to MMA, let alone a fight on the street. It is no longer required in many schools that a black belt be able to actually defend him or herself. All that matters now is how well they perform under IBJJF rules, which is a poor substitute for actual fight training. I've rolled with tons of higher belts who genuinely would be lost if they started getting hit in the face. The Gracies understood what worked in a no-time limit, one-on-one fight and they trained accordingly. That has gotten lost over the years, there's no doubt about that.
That said, the Gracies didn't invent shit. They took Judo and rebranded it, that's all. Through marketing, shady business practices, rule changes in their fights, etc., they managed to convince a lot of people that Helio not only created a new martial art, but that it was the only thing anyone needed to train. There is a strong cult mentality in BJJ and people still want to believe that story. To this day, most academies bow to framed pictures of the guy. Rickson comes from that same school of thought and has a strong financial incentive to push this narrative. There's also very obviously a ton of ego involved, considering this is a man who still lies about his fight record.
If you train modern sport BJJ 90% of the time and throw in just a little bit of striking, wrestling and MMA during the other 10%, you'll have something far better than anything the Gracies have ever done. Rickson is projecting here. He's wasted as much time focusing on 'Gracie Jiu-Jitsu' as the black belts he's taking shots at have on modern Jiu-Jitsu, if the goal is to be ready for a vale tudo fight. This is all without even mentioning the fact that gi training ultimately shouldn't even be a priority for just about anyone. It's something that improves submission defense and should be done largely for that reason, but only a small percentage of the time. Reliance on the gi is what is most responsible for the modern Jiu-Jitsu Rickson is complaining about.