growthexperiments-homepage-suggestededits-activated was used to show an unactivated state of Suggested Edits module on desktop (basically, guiding the user through picking topics and then tasks that they are interested in) and on mobile it is used to offer a tour that first time that a user taps on suggested edits summary.

I think given those use cases, we could stop using the user property with one of two options:

1. append a query parameter on user registration. So, the user would create their account, go to the welcome survey, and then land at Special:Homepage with a query parameter like se-unactivated. That has the downside of not working if the user visits other pages before going to Special:Homepage.
2. set a cookie after registration indicating that SE is unactivated, and then delete the cookie after the user goes through the onboarding on desktop, or after they tap on the module in mobile. If the user logged into their account from another device before going through onboarding, they would not see it. That seems like it wouldn't be a problem from a product perspective.