All ITX boards suffer from hot VRMs when system is stressed. I'm sure we all know heat is the biggest killer of electronics... so avoid heat as much as possible!
I would more say poor design of the pcb. No fuses. Replace a fuse and keep graphic card and other stuff. In my point of view they could use common fuse types which are easy replaceable by the user.
Chemicals - there lots of agressive chemicals around
poor design at the limit without reason. (although i still read the same bullshit with 8 layer pcb and other nonsense ... which hardly aids anything)
The wrong components choice. There are more durable parts and not. E.g. check power supply units for the temperature rating of certain parts.
Prebuilds with bad, bad mainboards(looking at hp microtower pcs)
ASUS as a brand - yet again i saw by chance gamers nexus video - where it seems again asus does have a faulty uefi - which caused wrong behaviour of the test suite. Or broken processors because of asus optimised settings (i hope you get my point - it's about mainboard which enforce bad settings - e.g. that x3d chip asus killed without knowing what they did) Asus seems to manufacture a lot of garbage in regards of firmware and settings. I wish people would share more how good or bad their mainboards are. Where the common faults are. (the point about gamers nexus - for some reason core parking does not work with windows + asus mainboard + swapped processor = wrong results for 9950x3d gaming benchmarks)
-- Some silicion get quite hot over many years and do not die. Temperature is only bad when the parts were badly chosen.