If it's more convenient, then what you're doing isn't wrong. Everyone has different input systems.

Mine is to email myself notes, and to use subject header as tags for later sorting. At some point I will setup an email scraper to automatically flag and parse these into actual todo lists.

But for now an email to myself just keeps me focused, and it just works!

Up your game. Create a WhatsApp group specifically for notes related to specific topics with another person, immediately remove that other person, and use the empty group chat as a note app. It's not on your phone and your tablet/PC, and you never have to bother remembering a note app exists. I may or may not have dozens of empty Whatsapp groups for this...

I find email is a better tool for that use case scenario.

At least with email, its cross platform, can be accessed by any of your devices and you can go back and do a search of your previous notes. I sometimes use it but only when I don't have access to anything else .... that or I'm just lazy.