Upgrading from 7 to 10 makes sense so long as the computer has at least a 1st gen i5 and doesn't have any major problems other than a hard drive (since you're going to have to upgrade to an SSD anyway to make it faster than a slug).
In fact, I just "upgraded" an old Gateway PC with a 2nd gen i5. We kept the motherboard, processor, and RAM and replaced everything else, including the case with this beauty:
https://www.thermaltakeusa.com/level-20-mt-argb.html
The thing looks sick, has a nice Corsair power supply, new SSD, etc. The computer is only used for basic internet browsing, paying bills, etc. so there was no need for a Ryzen CPU/motherboard along with DDR4 RAM. If the motherboard fails in the next few years, I will upgrade them to Ryzen and keep everything else. Basically it saved them the expense of a new motherboard/processor/RAM combo and a Windows license (so a total of $500 to $600). They'll have to spend it eventually, but if we can do that later down the road that's fine by them and me.
I've done this many times over the years, and you know what? They are sooooooooo happy when I initially upgrade them, but when it comes time to upgrade the motherboard/processor/RAM they are disappointed because they can't tell a difference. This is a situation when doing an upgrade makes sense.
When it doesn't make sense is when someone is a gamer and/or does other heavy tasks with the computer. They WILL be able to tell the difference between a 2nd gen i5 and a Ryzen CPU. But to a regular person like this, it's like replacing the engine and the brakes when all they have is a break problem. It makes no sense.