The biggest reason I don't maintain contact with people from my past is I was a much worse person in my past and I'm either embarrassed about my behavior or concerned that my shittiness is what led to our relationship in the first place. In any case, I find it's easier (and emotionally satisfying) to stay in touch with a couple people that I can have natural, unforced conversations with. Scheduling interactions on a…
What I've learned in the last five years is contacting people has more upside than not contacting them.
The worst thing that can happen after contact is a return to disconnection and the other person maintaining the same opinion.