The way you are wording about DOTS indeed confirms, you don’t have experience with DOTS. Which is natural that it will be hard for you, to get the performance comparison in any meaningful way.
ECS means Entity Component System. That requires to write systems and operates on entities, which is unmanaged data type. You must not think about Game Objects. This is different paradigm.
You would need swith your way of thinking from OOP to DOD first, to follow benefits of memory organisation hence benefits of DOD paradigm. Following with DOTS.
Using DOTS allows to process even milion of entities in crazy performant way. Getting benefits of burst and jobs, can result in safe multithreaded code with minimum effort. Enabling burst can alone gain you in some cases over 10x performance.
Writing code in SIMD friendly manner, gives you additional performance boost.
Jobs adding multithreading. And you can operate on native arrays if you need to, to get benefits of both worlds.
Entities is another step level up. But if you haven’t worked with ECS before, it may be steap learning curve ahead for you.
So the performance benefits are there, but need to be recognised and measured for each specific project.
You could run complex AI logic in paralel for example. For many 1000s of AI entities. Your CPU could barely feal it, if DOTS systems are designed in correct manner.
Or you could run compression and decompression algorithm for your networking layer.
Whole skills and physics of players also could be computed with DOTS.
I’d world is divided into some sort of chunks, where grop of players don’t interact with other chunks directly, then each group of players could be calculated on own thread.
Servers have these days many cores. Seems like waste of capability of the server, not utilising efficiently threads.