As the parent pointed out, purely-internal isn't what he meant. Distribution can be non-public, which is distribution nonetheless. Such distribution would require availability of source, but that availability wouldn't be public, if the original distribution wasn't public.
The parent seems to be focusing on "theft" (GPL violation) by relatively-unknown companies, which didn't necessarily occur. It's plausible that it did, but, even if the violation were corrected, since that correction doesn't require public release of source code, is likely irrelevant to the overall discussion.
You seem to be focusing only on publically-released software, which may or may not be the majority (by whatever measure).
I have no "side" in this, just trying to understand the points, which I've failed to grasp. Are you talk past each other?