I actively manage my footprint now, but I have to admit that getting started was a bit overwhelming. It's roughly on-par with switching over to a password manager for someone who was not using one before. It involves a lot of going through your inbox to locate accounts and then navigating a slew of different patterns for how to shut down your account, or at least to scrub information you don't want revealed from those accounts.
Once you get started, though, maintenance mode is fairly easy. Those "terms of use update" emails are very handy in picking up accounts you forgot you had and shutting them down. That, plus having a couple of templates handy to copy/paste when you get individualized outreach from sales teams.
The hardest part is that the majority of companies seem to have no idea how to comply with requests, which leads me to believe the number of people requesting removal of their data is much, much lower than I would hope or expect. It's generally incompetence, not malice. Or probably more accurately, it can be a complex technical task that requires interdepartmental cooperation to implement a good system, and few companies are jumping up and down to fund expensive or complicated compliance efforts in their sales and marketing teams .