I couldn't get the timing chain on with mine when engine was going together. After 10K miles, there was enough slack in the chain for it to work.
There's a reason that many foreign engines use chain tensioners. On the other hand, overhead cams use much longer chains.

I don't think the small amount of extra force exerted on the end of the camshaft will wear out the bearing, but it's the most visible thing so easy to blame.

R.