In the US, there is the whole "CONTROVERSY IS MONEY!" antics of the press, and the "Disproportionate coverage of niche ideologies creates compounding problems" that stems from that. (See also, the less than 12% of the population of the US that was demanding to reopen early for financial reasons, while the rest of the population said "Fuck that, stay home", and how it snowballed into the shitstorm we have right now.)
The more extreme, loud, and potentially dangerous you are about your ideology, the more the press just fucking LOVES you, because you are like a Jerry Springer guest. Giving you coverage makes their network stand out from the others, gets them more advert money, etc...
Perverse incentives, and damn the consequences of society.
Most people that are in favor of restricting abortion have more legitimate reasons for it, like Shonus points out. There *ARE* "Family matters" and "Makes Baby Jesus Cry!!" types who are VERY VERY vocal, and who stir up lots of support, but it typically happens that way because the more sensible types cannot get exposure for their views, and their views never get any traction with policy, because it is invisible.
See also, all the perfectly normal feminists, VS the feminazis on Twitter.
In order to get some of what you want, you end up having to pitch in with the loud and obnoxious trolls. This then leads to your opposition branding everyone with that brush.
Really, it's because there is a bias in the communication channel. Nobody wants to listen to or discourage a potentially cogent and calm point of view; they all want to be WARRIORS, and FIGHT THE BAD!