I think this ship has sailed. Services like nord or mullad are described as VPN products yet they are the products people are buying to route traffic into pornhub.
Usages exist inside contexts, and the context of the post you replied to was unambiguous. Changing it like s/VPNs/services advertised as VPNs/ would not clarify anything to anyone, and changing it like s/VPNs/proxies/ would be less clear (since the author was likely referring to commercial services, not servers in a network).
Yeah; it's not strictly accurate, but in a similar sense that it's not strictly accurate to call the typical copper Ethernet connector "RJ45", to say that a UDP "connection" occurred, or to say that a modem connects to a "DB-9" serial port.
I suspect the root of the problem is that over time, "proxy" has become strongly associated with application-layer protocols like HTTP, and after that shift it wasn't obvious what to use for something lower-level that encompassed a wider range of protocols/endpoints/conversations. In principle, "tunnel" would probably have been better (and a legible metaphor to boot), but that's just not how things shook out in practice.