This logic is flawed anyways. So if it cost less to cut animations, they should do it. If it cut cost to have less maps, less content, then they should do it. You could apply this to any product, sure you can cut cost, but then what's the appeal of your product. If a server browser is a selling point, then it'll bring in revenue.
You misunderstand how this works. There’s a difference between development cost and running cost. The point OP is trying to make is that in the previous installments, they used to have servers running game server instances. Because these instances were persistent, you could list and find them in a server browser.
The technology they use nowadays is very different. Game server instances are created on the fly and subsequently destroyed after each round. So there is no server browser because there are no servers that stay long enough to be listed and joined. This helps to conserve resources and makes it easier to maintain and scale the servers.
With portal the technology is a little bit different because the person that creates the server instance can keep it alive in between rounds. Because there are significantly less portal server instances alive at any given moment, it is not as resource heavy as the regular servers are.
So, yeah, introducing a server browser would require persistent servers which would cost significantly more money which would come from the running budget and not the development budget. So it’s not about how much it costs to create the feature, it’s about how much it costs to have this feature available.