It’s a command that pulls a whole bunch of useful system information and sticks it on one page.
Really, the biggest use of it is for showing other people your system- especially showing off. It’s a staple of “look at my system” brag posts.
But to be generous, there are (small) legit use cases for it. If you manage a lot of machines, and you plausibly don’t know the basic system information for whatever you happen to be working on in this instant, it’s a program that will give you most of what you could want to know in a single command. Yes, 100% of the information could be retrieved just as easily using other standard commands, but having it in a single short command, outputting to a single overview page, formatted to be easily readable at a glance, is no bad thing.
The UK isn’t quite that far, but it’s absolutely the dominant text messaging and calling app in the UK. Nobody uses the built in Android or Apple tools anymore, and I’m as likely to receive a WhatsApp voice call as an actual phone call these days.
I have Signal on my phone, but I’ve literally never had a cause to use it; I’ve simply got no contacts on there.