I think you two are talking about different types of support.
You're doing "tech support" at Project:Support desk—answering questions that people have about (for example) how to install it or troubleshoot it. That awesome community provides support for all versions, regardless of how old, so long as someone there knows the answer or is interested in finding out what it is.
The "S" in "Long-term support" isn't about tech support; it's about dev support. It's about things like porting new security patches back to older versions. There are very few people doing that, and I would not be surprised at all to learn that most (or even all) of them are employed by the WMF.
Or, to give an analogy, I have an old Mac Plus (with a whole megabyte of RAM!) in the basement, and I can certainly find a community online that would cheerfully provide "tech support" on how to set it up again. But it's no longer "supported" in the sense of new software or updates to old software being created for it. It is unsupported hardware, even if it's possible to get answers to my questions about it.