Just so.  If there are no limitations at all a griefer (or other malicious force, like an antiquated payment system that feels threatened by Bitcoin) could just flood bitcoin with inconsequential "non-transactions" producing hundreds of gigabytes of bloat and making bitcoin unusuable and non-decenteralized (because if Bitcoin required 200GB of storage right now in its infancy, who would run it??).  So there must be something to rate limit attacks.

Fees have generally served this purpose— but they are a blind mechinsm that doesn't really distinguish abusive use from good use, they just hope abusers use the network a lot more. But as there is more legitimate economic use and value people want the base fees to go down and not up.  Fortunately, some of the more obnoxious abuse these days looks categorically different from ordinary transactions: They create tons of 1e-8 value outputs (not 0 value, because the node software already blocks zero value outputs) which encode data.  By having a minimum output value it increases the cost of that bloat by a factor of over 5000 without impeding pretty much any normal transactions.  It also reduces the incidence of people getting irritated because they've received payments which cost them more in fees to spend then they're worth.