If you need to do a lot of inserts (or updates, etc), the slowest possible way to do them is to do them outside of a transaction. The fastest way to do them is to wrap them all into a single transaction.
This doesn't seem to contradict the comment you're replying to. They're suggesting wrapping operations into transactions in batches e.g. (just making some numbers up) if you have 100,000 inserts maybe you'd do 100 transactions of 1000 inserts each. I wouldn't call that "the opposite" of your one mega-transaction suggestion. In fact I'd expect it to still have most or all of the speed benefit of using one single transaction, or potentially even be slightly faster.
For serialized writers in any system I'm sure keeping a transaction open as long as possible is the ideal case for throughput, but there's other problems with that in a CRUD app no?