So what’s the benefit of adding a username at signup? If the user is able to find the community and register, what do they gain by populating that extra field? Are you just looking to collect a list of people you’ve referred in? What’s the benefit to them?
Invites typically serve the following purposes:
- Bring a person to your community and direct them to a specific topic - just entering your username wouldn’t achieve that
- Bring a person to your private community and grant them access - this would defeat the security of private communities
- Bring a person to your public community and automatically add them to a group to see other things - see (2)
In those cases they receive an email that once they click the link gives them a frictionless sign-in, the email address is already verified so they either use the suggested username, or pick their own, then move on.
You significantly oversimplified what will be required of users in your example, they’re going to need to remember lots of additional information and complete several additional steps:
Where to browse
What to look for when they get there
Who referred them
Then they’ll need to manually register and validate their email address. If there are any groups or privacy involved there’s also additional administration steps on top.
They don’t just “start the app” - there is no app which magically routes users to particular discourse instances based on referrer username, usernames aren’t unique between instances. Adding an app at this stage just complicates matters - if it’s a site-specific app they’ll need to also know what it’s called and install it, if it isn’t and you’re just referring to the Discourse Hub they will still need to install that and provide a URL.
That doesn’t sound particularly user-friendly.
With the invite link you avoid a couple of those pain-points, the where, what and who is contained. If you don’t like the length and complexity of that URL and plan to re-use a single invite there are a ton of URL shortening options out there. I’ve done this a number of times myself, putting links in presentation decks, on hand-outs and other materials.
The above suggests you’ve not thought this through at all. Consider the benefits to the other party and how realistic it really is.