I'm using phpBB to get my partner's dead forum back on track and I'm also a member of our forum. Currently I deal thematically with phpBB and Urls.
For me personally, "SEO Url" is a term that shifts the perspective of human being for whom the content is intended, to something technically abstract (which may be necessary). As a member of our forum I wrote in 2015 a informative post about the "Atlantic herring (Clupea harengus)" in german and another language.
I believe, if someone would notice this link, then certainly not in the form of
"www . xyz . de/viewtopic.php?f=1274&t=21".
I think more likely in form of
"xyz.de Atlantic herring"
and that's how we humans are, that's how we think.
Recently, I have completly reinstalled our forum and copied some old content into the fresh new tables. The IDs now have changed. All links to the former contents are now for the garbage. That may happen rarely, but also an aspect for "semantic urls" or "talking urls" or "HRU (human readable URL)", whatever it is called.
In this context, I would use also "SEO Urls", if it exists in phpBB version 3.2 and so I agree with this phpBB idea.
PS: I apologize if I have errors in my english