Indeed, and that's the trap that many autistic people have complained about - the medical model of autism requires that it be a collection of symptoms and deficits that makes the person "less than" in at least three ways. Aside from the ideological problem that poses, there's the practical one: somebody who's been masking hard from as early as they can remember and seeks diagnosis in their 30s, 40s or 50s has worked damn hard at constructing an environment around themselves - both in terms of people and their physical environment - which minimises any difficulties to the greatest extent possible.
As a result, it's very possible that they used to experience those difficulties, but have mitigated them over the years such that they no longer do (much). That doesn't make them any less autistic, it just means that they're the lucky ones who've managed to figure out a way to live with minimal hardship in this world through painful trial and error. However, unless they get a good assessor who's going to dig to try to figure out the real answer to that last criterion, they're going to get a "nope, you're not autistic" answer. Which, to somebody who's reached the point of being in that assessment, reads: "Nope, you're not autistic, you're just broken".
The central problem is that the DSM and ICD are, still, aimed largely at diagnosing children and extreme-support-needs adults.