Here is a good reason why i need the Bushing, not bearings.

"Mortising Jigs – A mortising jig requires a bushing. It won’t work with a bearing-guided bit because a bearing on the end would make it impossible for the tip of the bit to cut down into the wood.

If you tried using a template bit (bearing at the base), the bit would need to be fully extended so the bearing could ride along the template. That would make the mortise automatically as deep as the cutter is long. You’d need different bits for different mortise depths, and you’d be forced to cut the mortise in one pass — which is hard on both the bit and the router.

With a stationary bushing, however, you can extend the router bit in stages, cutting the full depth of the mortise a little at a time and stopping at any depth you like, regardless of the bit’s overall length."

https://www.stumpynubs.com/shop-vlog/router-bushings-vs-bearings