I have to agree, pe1chl.
But the density of devices with problems drops constantly. I build temporary wireless networks with tens of thousands of concurrent clients on a very regular basis - the last time I had problems with clients with k/r/v was in August 2017 (that was a Meru/Fortinet system).
On the other manufacturer's forum I have tried to get clear if the current problems are implementation problems that potentially could be fixed in the future, or if they are inherent problems in the standards and the implementation in the older clients, that can never be fixed.
I don't rule out completely that other manufacturers have found workarounds for those problems so it at least works acceptably.
Of course I understand that when an older device does not implement those protocols it cannot benefit from them, but at least these clients should be able to use the network as if these options were not enabled.
Until this is fixed, I cannot enable it because we cannot live with a part of the users who do not have connectivity even when their devices are old.
I have to wait until either those older devices have completely gone away (which may take 10 years for things like a HP wireless printer) or some workaround is implemented.
I expect that when MikroTik starts implementing the same things (largely from the same codebase) they will have similar issues for some time.
And as can be seen in the 802.11d discussion ("Country code") it looks like MikroTik does not consider working around other people's bugs a priority.