The King of Japanese isekai, Overlord is clear that Suzuki-san, the real-life Momonga spent a lot of hard-earned cash on gacha drops and other items playing Yggadrisil, even blowing his year-end bonus on game boosts one time. That sounds very pay-to-play to me.
As for Manuke FPS I don't know if Schwarz bought the Powered Suit he equips for cash but CP can be earned in-game by achievements. It's clear the Powered Suit is difficult to use requiring a lot of skill and practice (aka levelling up) so it's not the sort of thing a casual player is likely to be able to use well even if they were to drop real money on buying and using it. I see VMB as a game with a lot of noob stuff going on while the top-rank players whale on each other or take advanced quests to keep things balanced.
Generally the story is emphasising that Schwarz worked best as a team player in VMB and now he's by himself with his unique balance of skills and capabilities and zero magic potential which in this world is a big downside. Partying up for the Harpy subjugation quest showed him he doesn't fit in with the locals very well. He may get better.