I have not read every review here at TOM's but sometimes the author does point out the benefits from upgrading from an earlier gen hardware, be it CPU, GPU or any other component. Though, I have not seen a very older gen hardware comparison done in some cases. Not all SKUs are compared or included.
You have a point though, but we can also try to do the math, or make some educated guesses when it comes to comparing older gen hardware with the latest one (sometimes, but NOT always). Depending on the SKU, the performance jump will certainly be there, and in some cases the jump is pretty high with a new hardware.
But it also depends on which SKU we are comparing, and what architectural advantages the new hardware sports. FWIW, I'm still using a 4'the GEN Core i7 4790 (non-K) CPU. And even if I upgrade to say for example 9th or 10th gen, the new CPU would be definitely faster than my 4'the gen CPU.
But of course, I
won't be comparing the next-gen low-end Pentium or Celeron CPU with my 4'th gen processor, but only core i5 and above. But you can also check the GPU or CPU hierarchy chart here at Tom's , or even other websites to give you a rough idea on the upgrade/
performance uplift you would be getting.
I'm not 100% sure, but this chart might also help imo, at least based on the scores/points which are being listed in % value. But I know you are talking about REVIEWS here, so it would be nice if the author includes older gen SKUs as well. In some of the reviews they did include previous two or three generations of hardware though.
These charts are just for reference though.
CPU Benchmarks Hierarchy 2022: Processor Ranking Charts | Tom's Hardware (tomshardware.com)
GPU Benchmarks Hierarchy 2022 - Graphics Card Rankings | Tom's Hardware (tomshardware.com)
Anyways, regardless of my own explanation, your point of view still stands. It would be nice to see how much upgrade benefit comes from the next-gen or current gen hardware, coming from a
very OLDER gen hardware.
And like you mentioned, will it be really WORTH the upgrade or not ? This is the MOST important part. Sorry to bore you guys with my thoughts though.