It's not just inconvenient, I've been personally burned by this issue and am livid that Elementary OS markets itself in this way without a warning. Imagine installing Elementary OS on a bunch of PCs for charity only to discover that those users are going to be completely insecure in 2 years because you weren't informed. You might never meet those people again, and who knows what will happen to them. It's reasonable to assume a user knows how to update their computer once in a while; it is not reasonable to assume an "elementary" user knows how to reinstall their OS.
@pacifika: The Ubuntu LTS core will not help the built-in apps that won't receive updates (i.e. Mail, Web, Music, the Parthenon desktop environment), and the LTS core for version 6 (which was current until yesterday) is 20.04 LTS, so it will be obsolete in about 2 years. If you installed Elementary OS for a friend a week ago, that's not what you expected. So, you got 3 1/2 years on the long end of support and 2 years on the short end between releases.
