In which case people would just use putty or cygwin or openssh instead
Or they'll expect remote servers to implement whatever changes Microsoft will require for interoperatibility. We've been through this in the 1990-ies, when Microsoft's Internet Explorer was introduced with subtle incompatibilities in HTML-rendering...
Firstly I can see why you had to write "attempts", because it seems none of those actually killed anything
Well, a successful attempt is still an attempt: Netscape died. Kerberos survived because the world wised up by then — this very site had helped by hosting an anonymous coward's post documenting Microsoft's "extensions" to Kerberos so developers world-wide could implement them without signing an NDA of their own.
if they create an incompatibility here it is going to completely break their system making it such that Linux, BSD, iOS, Android, etc... can no longer connect to it.
Or not — depending on the nature of incompatibilities and the marketing/advertising... For example, the regular connections will work, but compressed ones will not (either at all, or requiring client to support some new compression algorithm). Or port-forwarding will be disabled (or not working at all). Or WINCH will not be sent to the remote servers, when the local window is resized — or, in the other direction, arriving WINCH will be ignored or misinterpreted. The possibilities for both honest errors and deliberate breakage are immense...