The level acceleration segment was removed from Pans Ops missed approach design criteria quite a few years ago. And I, for am glad about that - it was a nightmare because of the HUGE amount of additional area that had to be protected. There was no way that it would keep an aircraft in CTA around here.
I've seen some approach charts, from other parts of the world, that still show the altitude for level acceleration. Given that it no longer has a basis in Pans Ops, if you're confronted by it in any given procedure, it's probably still okay to use. The problem, of course, is that there'll be a whole raft of new captains who may never even have heard of this segment and, could, therefore, misinterpret it.
I can't speak for other countries but, here, the legislation requires the aircraft operator to determine obstacle clearance. It doesn't actually say that outright but, if your aircraft can't maintain a climb at the required gradient (usually 2.5%), then the implication is clear.