I think most people would want amnesia for certain memories like traumatic events. E.g. a romantic interest rejected you, or football quarterback throws an interception and needs to forget it to fully concentrate on the next play.

For most things, I wish I had more digital documentation of my past life. There were places I visited once that I wish I had photos for. There were people that were important in my life but I forgot their names and never wrote them down. I started keep a daily journal for the last 10 years and it's been so useful that I wish I had been doing that since I was child. If I had a git repo for everything single piece of code I wrote since I was a kid, that would be cool for me to revisit.

Back to your point, another type of purge that's useful are open projects that just nag you. For example, I had a "home automation" project on my todo list for years. In addition to taking space in brain, there were half-assembled open boxes of electronics on the shelf for years as physical reminders of that unfinished task. I finally decided to be realistic about my enthusiasm for that project and just abandon it. I sold the electronics and I feel better now. If I later decide to tackle it again, there will be newer and better technology anyway.

I also had a bookshelf of foreign languages for years that I thought I'd learn for foreign travel. After the COVID-19 crisis, I decided to give them away since I won't be traveling overseas for years. Now their absence no longer remind me of things I never got around to.

Purging bad emotions and unrealistic projects -- yes. Purging life data -- generally no.

I never really look back through any of it but when I do it’s quite nostalgic.

I think there is a happy medium and you can achieve it by keeping your inbox inside your trashcan.

This is not my idea and I have heard of it, in various forms, from different corners.

The idea is that all of your "important" papers get placed, as you receive them, into your larger (deeper) than normal trash can. I use a deep tray for this. It is basically a trash can that takes 6 or 8 months to fill.

When you fill the trashcan, you remove the bottom 1/4 of it and actually throw it away - since it turns out it wasn't important or necessary or actionable.

You can (and I have) created digital metaphors for this:

For instance, I dump my profiles directory, with all of my browsing history and bookmarks and so on, every month or so and then reset my browser. Then I delete those tarballs later when it's clear they were not important.

The key is this:

You can retain maximal optionality while still minimizing processing and sorting time. Just chuck it all into the "trash" bin and if it's really important you always now where to look.

So I chuck it in an archive. Gradually expanding storage at low prices means never having to think about deletion.

I don't use any of the systems for sharing tabs or history across browsers, because each has a different set of almost abandoned tabs. Sometimes "tab bankruptcy" is forced on me by software failure, and it's frustrating.

Notes, not really, there's a ton of them in Keep so I look up some stuff from time to time.

I have a massive collection in OneNote notebooks, and once a year it seems I check them and remember some good stuff, but mostly just how dumb I was before :D