I like the idea of specialty groups but the way it's been implemented in WSO Groups doesn't seem to work well. The energy trading group for instance would appeal to me but I don't see how you can have decent discussions in one endless thread (which seems to be what each group page is). I'd suggest the following:

Have groups in which multiple threads are allowed.

This starts to look more like a forum, so consider making it a sub-forum. E.g. Make the energy trading group a sub-forum of the Sales & Trading Forum.

To avoid having a mess of 1,000s of groups within a forum and fragmenting the site too much, consider having criteria based on which suggested groups are approved to be included as a sub-forum. Criteria that could be used are:

of total users or "parent forum" users that support the creation of the sub-forum (using a poll maybe)

% of forum users that approve of sub-forum creation

of days group has to gain traction independently before being included as a sub-forum and how long it must maintain traction after becoming a sub-forum (with traction measured by metrics such as daily/weekly/monthly posts/views etc)

Moderator discretion - you guys can probably tell if a sub-forum is too granular/specific when there are petitions to have sub-groups dedicated to "VW emissions standards enthusiasts with CFAs" or "shoelaces for I-Banking"