[tokamak-teapot]

Why do they need to be updated to newer versions? I don’t see what makes computers useless if they aren’t on the latest major release of the OS.

I’m running a 2008 MacBook which works just fine for its purpose (digital audio) and isn’t on the latest OS.

They’re still releasing security updates for High Sierra, which supports hardware back to 2009/10.

[Andrew_nenakhov]

Because all plugins, all samples and stencils on popular websites rarely support anything other than the later version. You can do without upgrading version of Sketch for maybe 6months, but then you'll run into problems, and in 18 months it'll be just what it is, cloud features gone, modern plugin versions gone too, no official libraries are of any use.

[salamandersauce]

The last High Sierra update was 7 months ago and it's now unsupported. It's not going to get anymore now that Big Sur has launched as Apple only supports 2 versions back.

So no security updates for starters, software slowly starts to leave behind old versions too.

[alphabettsy]

I’m not aware of a recent EOL Mac OS that did not continue to receive security updates for some time.

[salamandersauce]

And that time is two years after the next version comes out. That's how it's worked since Mountain Lion and High Sierra's time is up which is why it hasn't gotten any for 7 months while Mojave has received some.