The extreme left has a real issue with centrists, they can't stand letting them be. Trying to constantly pushing them out of that position.
The rightoids don't care that much about center oriented people.
Taking a center position yields you the least friends in online debates, but most people in real life have moderate views.
The left's problem with centrists is that they define de middle ground. If the left can move the centrist position, the extreme left can make itself look somewhat more normal.
There
was an "extreme left" at one time.
They had names like "the Baader–Meinhof Group", or the "Japanese Red Army Faction", & were very scary guys indeed.
Nowadays, some of the more radical Right (especially in the USA) like to use the label for those who advocate such horrors as a universal health scheme
, or support Unions "OMG!, How could they?"
I suppose everybody is entitled to have a hobby, & if calling everybody you disagree with silly names is theirs, may they have much joy of it!