The explanation as to why Warzone doesn't have issues with the player count is because rarely on warzone are there more than 10-20 players in the user's vicinity. It's not just player positions you have to consider though.
Technically, everything which is not in view of the Camera viewport (what the player sees) are culled (not considered for rendering). This is suitable in warzone and very effective because you rarely see upwards of 10 people at once. All of those other 130 are therefore not considered for rendering and have literally 0 negative impact on performance. In Battlefield, it's very often you see 30 or more in front of you. Although you may not notice 30 people, there are 99% of the time, more people on screen than you realise. However, it's not as simple as that either.
For example, there are more vehicles present and rendered in BF 2042 at any given time than Warzone. How many quads, Hovercraft, helis, Cars, Tanks, Jets? Ok there are a few more vehicles maybe 10 on-screen at any time. But... then the position and rotation of all of those items have to be scaled as well. When a tank shell fly's across the map? Everyone has to render it and all of the subsequent systems this triggers. For example, bushes may be pushed animated to the side by a grenade explosion or an ammo box animation has to be rendered for everyone near the ammo box. You can see where more players really add a lot more to the strain than just the players position themselves. 2042 is on another level compared to Warzone.
The tick count is an odd one. Actually, it can't really be factored in because even if the frame you're rendering is a frame not rendered using data directly from the server, the game still renders using predictions when data isn't available. So for example, if every other frame is guesswork (120 fps, 60 tick), your client is guessing where everything will be. This will be arguably lower or higher depending on what goes into the guesswork.
You can't add more players and have performance "scale". You have to lose some performance at least. It's not "free" and there's no technology that will make it free. However, it can be helped, for example with culling. Other common methods are "silencing" physics systems which don't move (turning their expensive calculations off), rendering objects at lower quality when further away (LOD). I'm very surprised we haven't seen Variable Rate shading implemented as an engine feature yet.
Moreover, everything associated with Physics is done on the CPU also. I noticed their vehicle physics systems have improved dramatically over previous games which will be more costly on performance.
I agree about the recommendations part. They are completely inaccurate. I think more optimization needs to be done and more tricks for rendering and passing only the needed data to fulfil a frame need to be added. But then when you look at the amount of missing "features" or "implementations" compared to other BF games, content was certainly cut for release. No questions asked. The gun customisation menu is a mess and would not expect that to be in an RC Build. The most confusing system I've ever used.
Nowadays the norm is releasing unfinished games and this is another great example.
