It’s not a question of what is necessary. It’s a question of transparency and consent. You must gain consent for giving Google personal data for tracking purposes.
ELI5: Why does the EU not just prevent Google from using personal data they receive by law in any way they see fit? Would that not be a lot more effective than requiring the millions of small businesses and small web devs to figure it out on their end?
The EU gives companies the option and only requires all this hoopla if you want to use the data for something else than the user requested. The "problem" is that Google does want that, as they are an advertising network, so they give web developers access to their tools but tell you that you have to ask the user for consent. That everyone totally forgets those warnings and somehow forgets that Google is an advertising network is on them, just like it is your responsibility what are random dependencies you download using whatever dependency tool you use.
If Google was banking its business on Europeans continuing to click "Accept all" in privacy popups, that would be worrisome – but I doubt it's true.