I hear this on many post-OGL videos about people exploring other systems, taking an objective look at 5E, and asking themself the question, "Could I walk away from this?"
And many people finally see the broken parts and weaknesses of the 5E design.
The required level dips and multiclassing to make classes viable are huge problems. A straight class without a dip here and there just doesn't work, and it does not even feel like a viable option. You feel you are holding yourself back. The base classes are boring without mix-and-match multiclassing.
And that is just one issue. The difficulty in playing a DM is another big issue and critical to the game's ecosystem. The amount of telling people to "just make it up" in a crowd that wants answers to basic questions. The ambiguity of spells and powers. The difficulty in creating and balancing encounters. The helpless feeling some weapons have. It takes little time to find these problems with a few play sessions.
Now that people have walked away, going back highlights a lot of problems with the system. These need to be addressed in 6E, but the backward compatibility claim and the few playtest releases don't seem like the "big solutions" the game needs.
The game is 10 years old, and there are better systems out. Patches and minor fixes will not last you another 10 years, not in this market with so much innovation going on. At best, I feel One D&D will last a few years, five at best, before the company realizes they are trying to support a 15-year old game that has fallen far behind in terms of ease-of-use, features, and fun factor.
I know, contrast this with a lot of OSR games which have emulated systems four to five times older, and those are still fun. You can't change what earlier games got right, and every edition Wizards has put out has eventually broke under its own weight and complexity, and the best support for their games comes from outside of Wizards.
Pathfinder 2E manages to build a system that keeps single classes viable, allows for incredible levels of customization within a class, and allows dips into other classes' powers as options without requiring multiclassing. The design is a hundred times better, balanced, and easy to understand.
Even Pathfinder 1E feels like a step up in a few areas compared to 5E, just in terms of system depth and options.
My problem with One D&D is if they keep it backward-compatible, they are grandfathering in a broken system. They need a complete rebuild and refresh of the rules. The door to other systems has been opened, and a good percentage of the hobby is off playing other things. They can look back and have perspective, and returning to a system with systemic problems will be difficult after people have seen and tried new things.
Playing other games is good for the hobby, and I welcome this.
But with One D&D, the bar needs to be raised, and the game's design becomes more critical with the SRD 5.1 in the Creative Commons. We need a revolution in rules, play, character builds, and how the game is played and thought about.
Without that creative refresh, you will be asking players to return to a 10+-year-old game that seriously needs a lot of rebuilding and cleaning up. That will be a massive ask for many after playing other systems and experiencing new things.
And in five years, they will really start to feel the problems of skipping this moment to rebuild the game for fun and ease-of-play.