There will always be contradictions with ich, as IME very few people actually QT and tons of people have successful tanks using fish that are certain to carry it (as it is natural).
[1]People have acknowledged that ich is generally present on wild fish populations, but not fatal due to not reaching plauge levels that can occur in aquariums.
[2]It is well known to become fatal in aquariums, given the right conditions. The assumption is that those conditions are simply being a closed environment (i.e. Aquarium), but [3] below contradicts that.
[3]It is also known that seemingly many aquariums/fish become resistant and/or immune to ich.
The question for me is I have no idea how people differentiate between [1] and [3], other than perception. The assumption that just being in a closed environment will lead to ich fatalities seems false since there are plenty of examples that defy this (some openly brag about it), and it seems that some aquariums can exist as if ich would in its natural state (or even dissapear?).
People will also often speak of "it being hidden in the gills!" in any aquarium that may have had signs of ich but never treated it, but IMO that is simply perception with no direct evidence. The implication is that the fish are still being "hurt" somehow
but that you just can't see it. It's a weird assumption, because if you think closed systems are the source the problem, arguing it is in some quasi state of being a "problem" but also not a problem... is kind of weird. Semi-plague? Mini persistent plague? Hmmmm....
I understand the drive to QT and employ methods to ensure [2] never happens, but there seems to be some real resistance from people to accept that [3] can and does happen frequently. Furthermore It often seems like the catastrophic [2] situation is often in tanks that employ the QT, but something "slips through the cracks". Makes me wonder is some tanks just become more prone to the severe issues when they are actually in an unnatural state (i.e. unlike [1]) of being completely ich free using strict QT procedures.
Anyway,
I am in no way advocating not using QT as there is far more than ich to worry about, I just find ich to be in interesting as you have some people going to extremes (that frankly many people will never do for an average aquarium), and others who do nothing (and know its there) and both can be successful.
As for the OP, that looks like a serious case of ich and not good for those fish, I would at a minimum treat them.