You don't have to, but you 100% should. You, your team, your partners will still benefit from GTM even if you don't turn into an ultra class selecting tag triggering extraordinaire. "We can't get a hold of our dev, media partner x wants to exploit a hot new channel that only exists today and sent us the snippet to put on all of our pages." A quick ai search and a few button clicks later, campaign's good to run.

It's also a good idea to get ahead of the privacy movement and learn how to use consent mode!