Actually there is some truth to that. You change the scrub radius and the load on the bearings by varying the offset too much from stock, which you could do when adding spacers.
Imagine if your front hubs are right in the middle of your tire's center line, and how the wheels move when turning right or left... And how the side-to-side load on the bearings would be distributed. Now, imagine that the hub bolts to the edge of the wheel. If you can visualize that difference, then you understand scrub radius, and how you might be wearing out wheel bearings much faster using an offset that varies a lot from stock.
Scrub radius - Wikipedia, the free encyclopedia
If you're correcting the offset to stock (or near stock) using spacers then bearing loads and scrub radius won't be a problem but still, some spacers also create more load on the studs and can cause problems with balance.
I don't think a quality spacer that is hub-centric would be an issue and as long as you don't vary the offset too much from stock the suspension geometry changes shouldn't be a big deal.
Then again, you know, poke and stretch and run 215's on some 11-inch-wide wheels that rub your fenders when you go around turns, all the other kids are doing it.
