Yeah that's a common myth. Svelte isn't some fringe alternative JS framework. It performs exactly the same functions and same structure as any React/Vue app, but does so with far less code and runs far faster since it's a compiler.
You're not going to find many brand-name companies using it because the PM decision-makers at large enterprises are always going to be many years behind and going with the "safe" JS framework leader at the time.
Well-known companies currently using Svelte: Apple [1], New York Times [2], Spotify [3] and GoDaddy [4]
1: https://twitter.com/mansur_ashraf/status/1204542852581273600 2: Svelte creator Rich Harris works for them 3: https://www.reddit.com/r/sveltejs/comments/f18n33/companies_... 4: https://svelte.dev