The larger a stake you have (in POS), the larger and faster you can grow your stake. It's a system that actively concentrates wealth to the top at the expense of the bottom. It is naturally predatory.
This is not true for most PoS coins. Everyone is staking at the same rate and every staker's part of the whole supply is constant. This is equivalent to having a constant supply and taxing those who don't stake.
The problem with PoS coins is not that. The problem is that it's very hard to have more than 100-ish nodes. Only Ethereum ventured into thousands of nodes territory, and, if you look at Ethereum's 70% blocks censored by the government, it doesn't work very well.