While I don't disagree with you on the benefits of a diagnosis, there is also a decidedly negative side to it. So much so that apparently it's a common practice

While I don't disagree with you on the benefits of a diagnosis, there is also a decidedly negative side to it. So much so that apparently it's a common practice to warn undiagnosed adults that they might not want to be diagnosed at this point, partly because they made it this far (to put it a bit bluntly) and partly because at least at this time there's not always much that can be done as far as treatment goes. That said, there's a high chance of comorbidity when it comes to things like OCD and AD(H?)D, and especially the latter can be treated. (I'm not a licensed psychologist, so don't take this as advice not to get diagnosed. Just providing a counterpoint.)