Law enforcement and security agencies need to be able to access any communication. This does not mean that they should monitor all communications.
They can eavesdrop on any phone call. They do not eavesdrop on all phone calls.
The problem with E2E encryption is that it prevents eavesdropping even with the standard legal safeguards (warrant, etc), while not being required for the privacy of users. It is only effectively a marketing tool to convince people to use services from providers they don't trust, although, of course, since they control the app they can still in principle access the data.