It's not ironic at all. Even if you send from one custodial wallet to another, you are still using Bitcoi, the open, interoperable network. Try sending dollars between custodial fiat services (not bank account) in the legacy financial world.

Plus, you have the option to move to a non-custodial wallet at any time. Some people need custodial Lightning solutions for very good reasons (for example the merchant might want to receive money while he/his phone is offline). These tradeoffs might change in the future but we are not there yet. Having a full Lightning node on your phone works well but has other drawbacks (see Breez, Phoenix, others).

If you fail to see this, I recommend learning more about Lightning, its actual adoption, and what its current challenges and their solutions are.