Miners don’t decide, unless they’re too big and too centralised. Case and point: the soft fork with version 29.4.2. The split resolved in a few hours, miners that didn’t update in time lost blocks to other miners that did update. This wouldn’t be possible on SHA256, even if was an emergency soft fork and everyone agreed that it’s not contentious. On the other issue: full node is best, pruned node is a compromise but it’s still better than no node and using someone else’s to transact and validate your own balance.