I oppose that because end to end encryption is still possible by anyone with something to hide, it is trivial to implement. I think governments should just take the L in the interest of freedom.
Traditional warrants couldn't retroactively capture historical realtime communications because that stuff wasn't traditionally recorded to begin with.
> It isn’t necessarily about mass surveillance and the implementation could prevent mass surveillance but allow warrants.
The implementation that allows this is the one where executing a warrant has a high inherent cost, e.g. because they have to physically plant a bug on the device. If you can tap any device from the server then you can tap every device from the server (and so can anyone who can compromise the server).
Which is why the clients have to be doing the encryption themselves in a documented way that establishes the server can't be doing that.
governments should just take the L in the interest of freedom
This was written into the US constitution. Unfortunately, most either don't know or care that it's all but ignored in practice.