The problem it solves is that typing on a phone is annoying, and that's a problem every other app has too.
The "problem" of people not being able to find you if you give them your handle instead? Based on recent experience of a lot of non-techy friends signing up and finding and following me with literally no problems, I'm pretty sure that isn't a thing.
And it's very centralized approach. IMHO typing in handles is a good approach for a decentralized platform. Also scanning QR codes on a conference instead of exchanging business cards. You don't need a seperate website for that. And noone wants to browse lemmyverse on a conference just to add someone (the issue they're obviously trying to solve with that.)
A small, but vocal segment of Mastodon users get very angry when someone creates any account discoverability service beyond what's built in to Mastodon. They do not speak for everyone.