Huh, I don't think this is correct. A lightweight Linux distribution such as Debian can make very good use of even a spinning-rust HDD, as long as it has enough available RAM that it's not hitting disk all the time. As I've mentioned in a different comment, even 512MB RAM can be more than enough _if_ you have no need for a web browser.
Could be rephrased as “I’m assuming you are using a fat IDE or equivalent such as any big commercial content creation software”.
But let’s call at least a modern browser par for the course for professionals.
For using 10 year old apps, or apps that haven’t been made a lot heavier in the past 10 years, obviously you won’t need more than a 10 year old computer.
The Penryn Core 2 Duo made the Macbook warm and noisy (the joke was that it's called Air because the fans push a lot of air all the time), while the Haswell-ULT chip literally pulls ~1W for the whole package at idle, and the fan often just stays off, and even when it's on it's very quiet.
And one other (but not as extreme) example was the 2011 Sandy Bridge laptops such as the mbp. Several years later if you got a new dual core the difference wasn’t that big.
(I’m now talking perf only, not temp, noise, idle power,... - I typically don’t even use laptops witiut the power cord attached)