I'll tell you what I tell some of my clients. "If it works for you, it ain't obsolete!"
Also, there is an ironic benefit in running a much older Mac. The older OS and the older hardware won't run the malware that's targeted to modern hardware and modern up-to-date macOS and later versions of OSX. in this instance there is safety in security by obscurity.
And, Apache OpenOffice does work on it, so I’m good.
FYI, this is a temp computer. I normally use an early 2011 (still old). But, at the moment it is on the way to the states to get the video card replaced. It is part of the non-voluntary replacement Apple does for free as long as I own the computer. I work in Papua, Indonesia where there are normally high temps, moisture and very fine dust in the air, even in my AC cooled-rooms. They may be on the hook for a while with me.