>giving more space to spammers doesn't solve anything
Sure it does. If 20 people legitimately need to get to work by bus, and your bus is a BMW Isetta, people aren't going to get to work. Simple as that.

>gives spammers incentives to spam more
No. That's stupid.
Currently, riding around, maliciously and, otherwise, aimlessly, on the Isatta bus costs $0.03. How would making the bus bigger (20 seats) be an incentive to ride aimlessly? wouldn't the little shit have to spend $0.03 x 19 to accomplish what $0.03 did on the Isetta bus?