Most people who use computers for the main part of their jobs literally can't spend that much if they don't want to be homeless.

Most of the rest arguably shouldn't. If you have $10k/yr in effective pay after taxes, healthcare, rent, food, transportation to your job, etc, then a $5k/yr purchase is insane, especially if you haven't built up an emergency fund yet.

Of the rest (people who can relatively easily afford it), most still probably shouldn't. Unless the net present value of your post-tax future incremental gains (raises, promotions, etc) derived from that expenditure exceeds $5k/yr you're better off financially doing almost anything else with that cash. That's doubly true when you consider that truly amazing computers cost $2k total nowadays without substantial improvements year-to-year. Contrasting buying one of those every 2yrs vs your proposal, you'd need a $4k/yr net expenditure to pay off somehow, somehow making use of the incremental CPU/RAM/etc to achieve that value. If it doesn't pay off then it's just a toy you're buying for personal enjoyment, not something that you should nebulously tie to revenue generation potential with an arbitrary 1% rule. Still maybe buy it, but be honest about the reason.

So, we're left with people who can afford such a thing and whose earning potential actually does increase enough with that hardware compared to a cheaper option for it to be worth it. I'm imagining that's an extremely small set. I certainly use computers heavily for work and could drop $5k/yr without batting an eye, but I literally have no idea what I could do with that extra hardware to make it pay off. If I could spend $5k/yr on internet worth a damn I'd do that in a heartbeat (moving soon I hope, which should fix that), but the rest of my setup handily does everything I want it to.

Don't get me wrong, I've bought hardware for work before (e.g., nobody seems to want to procure Linux machines for devs even when they're working on driver code and whatnot), and it's paid off, but at the scale of $5k/yr I don't think many people do something where that would have positive ROI.