There are a few things mixed up here. I'll leave ETH out of it because that is somewhat more complicated (the block limit is variable) and it is close enough to just stick with BTC for simplicity, but with BTC the auction is the ONLY mechanism for allocating space, meaning "congestion" is effectively normal. When demand exceeds supply, the only solution is for the fees to become very high at which point the wealthy can push others out.

With RC, the pools also limit usage dynamically (if calibrated appropriately) meaning RC costs will increase and usage will decrease (because more and more accounts will be locked out of transaction periodically, or will need to reduce their usage to avoid hitting the cap). Therefore, any congestion should be only a short term transitional phenomenon (vs periods in BTC when fees have remained high for months, and could in theory be permanent), and much more muted in magnitude.

That being said, the wealthy can still win out with RC because if demand is high relative to resources, RC costs will go up and you would need a lot of HP to do much of anything.