The fee priority mechanism was just node policy. As I recall, miners had mostly all removed it from their nodes so it was eventually removed from the reference client. Developers aren't really in a position to force new fee policies on miners.
they forced segwit......................
No, they didn't.
Miners activated Segwit. If miners were "forced" by anything, it was the threat of BIP 148, which was never part of the reference client. Many Core developers were opposed to merging the UASF -- on such a rushed timeline or at all -- and it never was.
Miners made a conscious decision to activate Segwit to prevent a chain split with users enforcing BIP 148. Core nodes would have sided with majority hashpower either way.