It actually is working though in the MLB and USL, because the seasons are ongoing. If they flat-out cancelled the season because of covid cases then you can say it didn't work. But to say that now is premature.
They wouldn't be able to have the games without a bubble. The MLB and USL are proving it doesn't work.
As to the games themselves they have looked and been played with the same intensity as normal playoff games. If you can't see that then that's on you.
I think you're also missing the point about the playoffs. When you ask any hockey fan what they think when you say 'NHL playoffs', nearly all of them will tell you intensity, crazy atmospheres and exciting games. Those three things are a package. If you take the atmosphere out, it doesn't make it a complete package anymore.
The NHL can call it whatever they want, but there is no way you can watch last season's playoffs side by side with what is going on now and act like it's close to what it always is.