While I understand why some people are upset, I think this is a good change. I do agree with the one post saying that the wording is weird. I think the intent is really - these new bosses should have new mechnics that can be met/beaten by different champs from the current meta.
I DO NOT have any max hp champs, and was able to beat them. However, I used TM to get around the mechanics...
They also did tell us they were going to be tuning them. Personally, I think this is DT, end game content which the intent was to require new teams/comps/etc. to beat, and I think they have that now.
edit - to clarify my spend level as a lot of folks make assumptions it seems :-), I'm a light spender (monthly gem pack and raid card).