Yes, this is what I think a lot of people with good health or relatively straightforward conditions simply don't get.
I have a health condition, as well as one or two linked complications, which could easily be identified as an increased risk-factor for almost anything health-wise that could beset me, short of being run over by a steam roller.
Thus when 'existing conditions' are not covered, that means that any insurer could argue that a vast swathe of different new health problems might have been potentially linked to my 'existing conditions' and leave me high and dry - even if they had already charged me a hefty premium because of it.
I don't necessarily disagree with those who say "If you can't afford insurance, you can't afford to go abroad", but I hate how this is often said so flippantly and smugly, with the clear undercurrent of 'well, if you can't be bothered' to organise/save/pay for it; ergo it's basically your own fault if you can't go abroad.
I would hope these same people wouldn't 'helpfully inform' a wheelchair user that "well, if there's no lift, then upstairs just isn't for you!" - before going on about how wonderful upstairs is, how everybody should make an effort to go there and that those who don't take their children there are massively letting them down.