I doubt he is saying the spacers themselves are hard on those parts. I think what happens is since you do not bring the centerlink down you start to take the tie rods to the extent of there travel and potentially bend them. Same with the cvs but if these help with the camber it will take care of the cv joints somewhat as well. Now if you have manual locking hubs cvs should last some time any way. Gen 2 hubs are always locked but can have manuals put on to them I think.

89 2dr 3.0 AT, manual hubs. 33x12.5 MT
gen 2 coils,Cranked front tbars
Dons rocker protection, Front/Rear Bumpers. ARB rear locker, 2" BL, Beefed up skid plates/trailing arms. Gen II uca, 2 Bouncy seats www.youtube.com/TagGeorge