Just create a mutlireddit of your subscriptions by going on https://old.reddit.com/subreddits/ and clicking 'multireddit of your subscriptions' on the right. Bookmark that link and voila, you have a backup of your subreddits for your new account.
That seems like a solvable thing with a 3rd party app/script.
I reroll every time I am banned from a sub I like because that sub notices I play in other subs - that whole “thing” is horseshit to me. So I just reroll to get around that autoban bot.
I used to think so until I decided to reroll my old account into a new one, and it was such a pain re-subscribing to all my subreddits again.