Comment by jchw
The point is that we can improve latency of even old machines by simply attaching a display output that supports a higher refresh rate, or perhaps even variable refresh rate. This can negate most of the unavoidable latency of a compositor, while other techniques can be used to avoid compositor latency in more specific scenarios and try to improve performance and frame pacing.
A new display is usually going to be cheaper than a new computer. Displays which can actually deliver 240 Hz refresh rates can be had for under $200 on the lower end, whereas you can find 180 Hz displays for under $100, brand new. It's cheap enough that I don't think it's even terribly common to buy/sell the lower end ones second-hand.
For laptops, well, there is no great solution there; older laptops with 60 Hz panels are stuck with worse latency when using a compositor.
Plenty of brand new displays are still sold that only go up to 60hz, especially if you want high quality IPS panels.
They aren't as common now, but when making a list of screens to replace my current one, I am limiting myself to IPS panels and quite a few of the modern options are still 60hz.