The other main issue is bandwidth. For a CRL, Apple has to serve the full list of revoked serial numbers (or some shard of it), even if 90% of users don’t have 90% of the revoked apps installed. I can’t remember where I read this, but I recall that after the Heartbleed disclosure one CA saw their CRL traffic grow by some number in the gigabits per second. Bandwidth is relatively cheap, but still not free (without even considering the argument of “do I need to know that the cert for an app that I will never use is revoked?”).