They have shape tools on the roadmap for this free image manipulation app, until then we'll have to use the two-step method of stroking a circular selection or use a more dedicated drawing app.
In any case GIMP 3.0 is a huge rewrite under the hood and seems to be attracting more contributors now, which is a good sign.
More contributors is great. Whilst I think sticking to C will always limit its outreach somewhat I think the reliance on GTK2 was probably even worse for anyone brave enough to dive into that spaghetti mess.
The cynicism is well deserved. They have been on 2.99 for years.
That said, I have been using 3.0RC1 for a bit. It ships packaged with my current distro and has worked well for me. This release should be quite usable even though 3.0 has not officially shipped.