More numbers != Next gen.
Next gen is the hardware itself thats next generation. The actual technology on the boards and chips themselves that are so much smaller, faster and more efficient than they 7 year old predecessors. The RAM while lower is much better and more efficient than previous consoles. The CPU is lightyears ahead in terms of speed, power and efficieny and will do so much for consoles that it's going to change how console games feel. It will be much smoother and capabale of more fidelity than before. The SSD while slower than the PS5's is still lightyears ahead of the terrible slow HDD's that were standard before. Trust me, you'll notice the difference in everything from UI speed increase to game asset loading major increase and load times reduced by minutes in lots of cases.
I get why people are skeptical of the Series S and how it could "hold back" development on 3rd parties and even exclusives, but i dont see it. Even last gen, if there was an advantage to be had on PS4, most developers went for it. They usually had higher quality graphics and better framerates. The PS4 versions were just better overall. PC versions are usually always fully featured just because they can and even the Switch got a lot of ports of big games being a sub 1tf machine. That said, while its the least powerful console, the S will be no slouch for a 1080p machine and developers should have minimal issue scaling to it from X or PS5 with the tools provided by Xbox, it just takes a little talent / effort to not make the S version a pile of dogshit.
If you get a PS5, you'll get the best possible version of that game as is possible on the device, independant of the PC or Xbox or Nintendo versions. Good developers go the extra mile to make sure their work is at its best on each platform they choose to develop for. The onus is on the developer to prove their work they are selling to you, not the tools they chose to use to provide it.