I’m not quite sure what point you are making.
bbPress does not support blocks, it may do at some future stage, but it does not do this now.
Wordpress support uses bbPress and has a fix they have decided to do in order to support blocks.
I did some experiments to see if I could get blocks working with bbpress.
I said in the other thread that I could not get blocks working with 19.7, so it is probably not surprising that you couldn’t either – I’m not sure why you thought this would work. I did get it to work with 16.7, but I have not tried it since 6.8 was released (nor do I plan to).
It is up to plugin authors to decide what they wish to support within their plugins, and whilst you think it would be good to be able to use blocks, this is entirely up to the authors of free software.
Whilst personally I would not wish to impose blocks on my forum users, as I find it unintuitive, I would support adding the capability for those that do want it.
For the time being, unless you can get it to work, then you have the editor as per this forum, or the visual editor which can be added using the bbp-style-pack plugin.