Certainly so. I think the six encounter adventuring day is something that is horrible at low levels and just a slog at higher levels. I haven't played in very high level games of 5E so I don't know if that is addressed there, but I think people have consistently said that high level play is all over the place since it wasn't playtested nearly as much.
Low level play simply can't handle six encounter days because the characters don't have enough resources that can be recovered with a short rest (outside of classes like the Warlock which is all short rest) and run out of hit dice. A low level wizard runs out of spells very fast, and uses nothing but cantrips from then on. An experienced player rations those spells out, but that can result in the party taking a huge variation in damage or other resource depletion if they don't guess correctly or if there's some bad die rolls involved.
My experience is that you can eventually hit a sweet spot where characters can do more and have enough resources to do more encounters over time. Does that get to six? Consistently? I honestly don't know. I don't know if there's any consensus on it, really. How that scales best is really anyone's guess, and that's a problem. And that's why I'd say that changes to the adventuring day and the rest system are really important to keeping the game fun across all levels, not just some that are narrowly defined.
I would also say that planning an adventuring day as the GM so that the game is interesting and not just filler combat is also quite challenging for six encounters. And that's not even getting into fitting all of those encounters into a single game session.
So yes, I think there's a lot that needs to be done to address the issue. I also know that, while there isn't universal agreement with this idea, it's also something that's been discussed since the game first launched, and many people have made the same points as I'm making.