Should simple online utilities require a signup/account?

Hey Product Hunt community!

I'm currently building OnlyBills, a free GST tax invoice generator. While coding, I made a strict design decision: No registration. No databases. Zero logins.

All user data, client profiles, and billing history stay saved locally inside the browser's storage (we support JSON backups so you don't lose data when clearing cache).

I did this because I hate having to create yet another account just to generate a quick PDF. But I've had colleagues tell me: "You're losing out on building an email list for marketing!"

What are your thoughts? As a user, do you appreciate tools that let you skip signups entirely, or do you expect to make an account for everything?

Would love to hear your experiences as both makers and users!