Speaking as someone who had to maintain a Discourse instance for two years:
It’s mature and proven but still a lot of work to maintain.
We went away from Discourse because it was not a reasonable use of time and not trivial - so you needed someone with dev skills to take care of it.
Slack was the alternative.
We use a service that creates a static page from all Slack conversations so this way we have a searchable index and can work around the messages disappearing due to the free plan.
There are other limitations but it works well enough for a community of about 4-5000.
