Crazy Extremist: "We have to kill all the kittens!"
Sane 'Extremist': "What?!? No! That's crazy! There's no need to kill any kittens!"
Moderator: "Now, now, none of that namecalling. Compromise is called for. We'll kill half the kittens."
A decade later, as the sane extremist has been repeatedly berated for their extremism, the "kill half the kittens" compromise has become the status quo, the best of a bad situation as it were. The yelling dies down.
Whereupon the crazy extremists again call for killing all the kittens, and the moderator insists on a "compromise" where only three quarters of the kittens die
The sane extremist then - understandably - goes ballistic, and is universally put down for being so impolite
The "middle grounders" are in fact, helping the craziest extremists.
In the presence of effective always-middle-grounders, then, the only reasonable approach is to be even crazier than the other guy. Otherwise, the middle grounders eventually hand all the ground to whoever is craziest.