I think that if someone is allowed to spam the offer book with 30 offers, spanning across all possible price ranges, other peers won’t stand a chance of completing a trade.
Suppose that I have a lot of money to spare, so I spam the offer book with a number of different kind of offers to buy BTC. I can afford the trading fees and there’s not really a problem about that, because my offers are legit. I do indeed want to buy ALL that BTC, and I make sure that all my 30 published offers are at the top.
Of course it’s my right to publish offers with any kind of market price deviation I want (there’s no denying that). But the problem is that my offers are too many and I’ve also made sure they cover all the price spectrum (I’ve published offers to buy from 0.01, 0.0150, 0.02, etc).
It might be bad for other makers, unless they offer a better price than that “spammer”, and that would be good for takers.
Providing a lot of offers that could get taken by someone is not bad. Unreal offers, like selling BTC at 100.000USD or buying at 1USD, might be bad for the network as they require to be broadcasted and noone would like to take them, but keeping offers between the 0 or 10% spot range is not bad.