Just note that for the non-wealthy and non-road warrior, the real leverage is in churning cards - getting new cards, meeting the requirements for the spend bonus, then moving on.

Assume for simplicity that every card had a 40,000 point sign-up bonus. This means that if you spend $1000 a month, it would take you over 3 years to get the rewards that one additional card signup would get.

If you choose not to play the churning game, that's fine. But the rewards you ultimately earn will be modest by comparison.