In PR the compromises all happen in the backroom deal to form a coalition. After that they have the votes they need and don't really need to care about anyone that's outside the coalition.
In FPTP I can call my MP and complain. I'm not one out of tens of millions of votes, I'm one out of thousands of votes. A small group of people in a riding can make the MP pay attention because they could lose their job if they don't. We influence the MP, the MP influences the party. And the party needs to listen to the MP because the seat doesn't belong to the MP, it belongs to the MP. The MP could cross the floor, go independent, or even join another party, and the party loses a seat. The power dynamics flow up from the people. The people can remove the MP and the MP can take away a little bit of power from the party.
In PR, the MP exists only for show. After the election that party has X% of the vote and has X% of the seats. The job of the MP is dependent on sucking up to the party leadership. They will vote for or against what they're told to by the party leadership, so what's the point of them? Just have the party leaders there and when they vote for, X% of the vote is for the legislation. Or conducts it like a courtroom, the parties hire the best advocates they can find to read the rationale for voting for against a piece of legislation.
PR has legislative assemblies only to provide a show of representation, put people in those seats don't represent anyone except their party.
The proof is in the pudding. Israel, EU, both PR systems, both susceptible to far-right coalition politics. The UK on the other hand will soon have a center-left government while the rest of Europe will be under the far-right influence of the EU parliament. A hard Brexit was a mistake, but what's going on now only has the EU proving idiots like Boris Johnson and Nigel Farage to be right. I mean Nigel Farage ever being a MEP only proved what a clown show a PR parliament is.