I think this discussion has become a bit too toxic, but I feel like there's the need to clarify a few things here.
This whole recent "incident" didn't spark from the fact that DT uses a lot of backing tracks for their live shows. That's been the case for the last 11+ years, there's no real reason for it to become a problem "just now". And IMO, there's nothing wrong with that, as that's the kind of show they want to present and they feel like it's best to do it that way. They aren't a 10-piece band with multiple singers or two guitarists/keyboardists, etc. They might do a few exceptions (Metropolis or TCOT intros) but other than that most of what you're hearing, specially in the playing/instrumental department, is being played live on the spot. And the've said that (specially Jordan, most recently) they approach it in the "let's reproduce as much as we can live with our two hands" fashion. Anything else that's added to the piped in tracks is because there's layers and layers of other stuff that they can't simultaneously play anyway. Again, there's nothing wrong with that approach either.
So, what's the big deal then? That it's become apparent to some people that there's certain spots in one specific song where it seems like the "backing track" vocals are doing the heavy lifting at least for those couple sections. Now, if you look at this carefully, I'm using words like "it seems" and so on because we can't ever be 100% sure of what's happening without actually being there with the band and crew and to see what gets piped in and what not. However, there seems to be some evidence to support that statement, coming from different people at different shows and shot from different angles. And that's a completely different topic/discussion than just them using backing tracks to enhance their performance, which shouldn't be the main issue at discussion.
The real issue instead is should the backing tracks overpower/replace what is actually happening live? Because then it just doesn't feel like an honest performance anymore, even if that's just for a few seconds anyway. And again, full disclaimer: I don't have any issues with them using backing tracks at all, and I'd say most people here don't either. But that's not what this whole "incident" is about.
And as for James' response, I have nothing but love and respect for him and all he's done for the band in his more than 30 years with them, but he quite didn't address the real thing either. Is he lip-syncing? Maybe not, and he obviously said he isn't. But again, the real question here isn't if he's lip-syncing, but if he's "cheating" for a couple bars on that particular song and letting the piped in vocals handle it while he prepares for the next section. And that he didn't address at all, he just started cursing people who brought things up. And that's at best a fallacy.