But requiring an external tool is not ideal. Especially bots, which are hosted by a 3rd party that need access to certain parts of your channels.

Why would someone other than the server admin host the bot?

It's not ideal, but shipping a mobile and desktop client that are literally incapable of displaying the same channels in the same order is also not ideal.

That's not the same. Unless you're adding one role per channel, and then it's quite unwieldy. For example, we're not going to set up a role and have everyone else self-serve add that for a channel for an outing, a specific feature/bug, etc etc.

How do you get the right subset of employees into a channel in Slack? The same amount of work split the same way can accomplish the same thing in Discord.