This is pretty much my take.
Do I like VAR? No, I think it is possibly one of the worst examples of technology implementation I've seen from a multi-billion dollar industry. It is laughably bad. I have a long list of things that I would change if it were up to me. Either that or, like you, have it summarily dismissed as a failed experiment.
That said, it never ceases to amuse me how hilariously short people's memories are about what life was like before VAR. If I had a penny for every time I heard "the technology is there, why don't they use it?" I would have been able to retire by 25.
Remember the Reading ghost goal? When Kieran Gibbs got sent off? Nani's handball goal v Spurs? Henry v Ireland? People have been having kittens over decisions like this for as long as time immemorial. The one thing you can say is none of the above would have happened in the VAR era.
This Coventry offside is not an example of an obviously incorrect decision, it's an example of a decision people just don't like. I can't blame them for that, I hate it too. But it's not a problem with execution, it's a problem with process. Which are two very different things. And it's United, so that naturally fucks people off even more.
I've said it before, the problem isn't the decision it's the delay. In my opinion (and it is only my opinion), they should have only allowed VAR to get involved in offsides if the technology was capable of enhancing decisions at no detriment to the game. It wasn't and now they've given people a reason to hate it.
It would have been so easy to make the VAR introduction more gradual and measured. First use it for exceptional errors like mistaken identity. Then maybe timekeeping. Then if people think that's worked, just give referees the option to look at a screen to review reds/handballs. Then, when the tech was up to it (it isn't today in its current state) offsides. Instead, they brought it in to do a whole raft of things at once with untested chaotic processes, so much of which is not fit for purpose.
They should have had us begging/complaining that VAR doesn't get involved enough because they are overly cautious, but now the genie is out of the bottle and they've properly fucked it. If they aren't going to get rid of it (because they won't), it now needs a total overhaul.