Its one thing to say i dont like the idea, but stating it will be a problem,
without having a crystal ball/time machine is flat wrong.
and no, a fan that doesnt run doesnt die, and nothing will evaporate at normal room temps,
especially not the synthetic based lubricants (using solvents to keep them "liquid").
e.g. ever used silicon (lube) spray around the house/car?
never seen it dry out, only mechanical wear or solvents will remove it.
a sealed bearing wont have that problem, as lube cant get out, and synthetics dont go bad (its lab made for that reason).
proper fans can handle up to 60-70*C and about 40-60* continuously, and even if i dont use the max number (about 300K),
even at 150K thats
17y @24/7 use, and if i go down to 50k, that virtually every brand name fan i can buy, will do,
thats 17y @8h/day.
and i doubt the fans that died were artic/noctua (or similar quality) and most likely not even warranty of 6y or higher...
so until you have supporting info, showing that more than 1-3% of all MB fans fail within 5-10y, there is no issue.
outside that almost every decent board uses plastic pins with hooks (or similar) that just get pushed thru,
and if you mess up any screws? to quote my father: wrong tool/size or not enough light