AFAIK, mining algorithms are designed to decentralize the transaction processing and production of coins in the first place.
But it naturally strongly tends to concentrate the minig power since the reward depends on it.
I think this is rather a consequence of the "winner-takes-all" nature of the Bitcoin block reward.
After all there is only a remuneration for the first miner, who successfully mines a block, which makes mining only economical
if you either have a large percentage of the total hashrate or are part of a mining pool that enables
you to partake in the block reward even if you don´t mine the block yourself.
In part sure, but I wouldn't underestimate the effects of economics of scale.
Large mining operations can stay profitable at lower margins, which in turn makes it harder for smaller miners to remain profitable, further feeding into the profitability and thus growth of large mining operations. I'm afraid this is inevitable with pretty much everything that is turned into a business though.