Dunno, if you have the right combination of rim, tyre and the right equipment it is easy. Trouble is there is quite thin info on what works and doesn't work. Getting hold of the correct stuff isn't that easy. Compared to fitting clichers it isn't as well understood or easy to do. Remember, on yacf (which has on average higher cycling "know how") we have more than on thread about how difficult it is to fit clicher tyres.
I went with Schwalbe Ones (28) on Archetype rims (stan's 21mm tape, valves, injector, Schwale Sealant and mounting fluid)
I managed to get all the bits in one hit @ one of the German online suppliers - and it all seemed to go a lot easier than your experience.
Regular tyre levers (although with a bit of fighting I might have got them with thumbs)
First inflation with track pump and no sealant seemed to hold pressure so the beads must have seated right away.
The only issues I had on first fitting was sealant clogging the injector between doing front & back wheels, and one of the valve locknuts needed an extra tweak as my original casual 'finger tight' wasn't quite good enough.
I read somewhere that road tyres needed only 30ml of sealant (60ml for MTB) but as I was on 28s I went with 45ml
On occasion I've left bike for a week or more then ridden without checking pressures and certainly things have felt a little more 'cushioned' than usual but not 'squirrely' even when subsequent checking showed less than 60 psi.
Think they went from 95 down to about 70 over the course of PBP.
Had one single visitation, not dissimilar to Frank's experience... but hissed for longer and liberally coated inside of mudguard with sealant before holding about 10psi. Re-inflated to 70-ish with the mini-pump at roadside and rode home without problems. Rode another 200, also without problems, before dismounting the tyre to check it thoroughly for internal damage and replenishing sealant.
Maybe I was lucky with my rim/tyre combination first time around but they certainly get a
from me.