Unless the answer to "What would you say y'all do here?" is constantly changing I don't see why the TOS should be changing. To use Patreon as an example, while the details of how their systems are built and the business is promoted is likely in a continual state of flux, what they do is somewhat fixed so the terms by which someone interacts with the business should be somewhat fixed as well. Unless you're making a big change to features or the nature of how users are to relate to your business (eg: when Slack pivoted from being a video game company to a group chat company) I think making TOS changes (even if it's what everyone else is doing) speaks to instability, leads to a lack of trust, and generally gives the impression that the company doesn't know what it wants to be when it grows up.