Your experience and mine were very different when it comes to these feats. I'm curious why.
A fairly recent example was a Variant Human Fighter that took PAM at level 1. They attacked for 1d10+3, 1d4+3, and often and additional 1d10+3 each round. At 4th level they took GWM - and acquired Gauntlets of Ogre Power. At 5th level they were sometimes attacking 4 times in a round for 4d10+56 damage (or as low as 2d10+1d4+42). The DM put a magic polearm into the game for them to find a bit later, but it was a +1 weapon with a minor perk on the side. They had various tricks to enhance their chances to hit, including ways to gain advantage and ways to gain the effects of bless (they hired a low level spellcaster to follow them around - from a mostly safe distance).
The PCs in the game were efficient, but not super optimized builds designed to bust the game. This PC was the central damage figure and provided significantly more damage than the other PCs - especially when it came to taking big targets down. They also used their subclass features to control the battlefield (it was a Homebrew - but generally less powerful than Battlemaster - it created leadership auras that discouraged enemies and encouraged allies).
At 11th level the attacks increased and the PC was utilizing a 25 strength from a belt of Fire Giant Strength (which they sought out - they wanted higher strengthm researched how to get it, and convinced the group to go adventure for it) - and picked up the capability to enlarge to large size a few times a long rest. The campaign has been on hold for a bit, but this was a pretty typical experience with PAM and GWM in my experience. It would be pretty easy to duplicate it in BG3, for example.
Why was the experience you referenced so much worse? And why would someone capable of using any weapon in the game select a mace?