Never Split the Party

Alright, we've all heard the rule, never split the party. Yep that's great advice because the way TTRPGs work its really just not viable to do that since encounters are balanced around having the full party there to deal with it. So my question is, are there ways to make it where splitting the party isn't a death sentence for parties? My number one rule for being a DM (at least for myself) is to let everyone have fun. A sub rule of that is the rule of cool. If my player comes up with something cool I want to encourage that, so I tend to reward it by giving them some kind of bonus, taking the story places it wouldn't normally, bottle cap etc.

I think there is a lot of story and idea gold in the idea of actually effectively splitting the party. But I find that its near impossible to not immediately wreck a party when the split up. And if I did find a method to do that, I cant think of a believable way to convince the players that it is actually ok to do so.

What are your thoughts? Have you ever managed it as a player or a DM? Any ideas on how a campaign could be designed that allowed for it? Etc?