Signal is objectively a far better choice than SMS or WhatsApp and all the options I’m aware of. I dunno what OP is angling at either.

The only easy to use E2E encrypted chats are centrally managed, eg: Signal - and even getting friends and family members to move to that is hard.

While a decentralized fully open source self-hosted solution would be great - that shits just not possible for 90% of people. Apps succeed or fail due to barrier of entry and ease of use, and the decentralized options typically have far less user-friendly apps, far fewer users, and often require tech know-how like choosing a federated server or even configuring your own online storage or server (egs: Matrix, Briar, StoneAge). Some bring up Session as another alternative while failing to realize it is also centralized if you want push notifications (which most users do).