Steem accounts already have a unique id number. You were actually really close with your example! Yours is 32490.
Top thing in the left box https://steemd.com/@snowflake
BitShares has a referral system. I'm a little fuzzy on why Steem doesn't. Referrals are a little tricky sometimes, because if refcodes are used in URLs it can lead to an impression that the site is a scam or just sponsors spam. But in the interests of incentivizing another front end or app to create accounts, I think it would be great if it worked something like how registering through BitShares' OpenLedger gives them the referral.
An limited invite system may also still be useful. Though really the phone registration gateway needs to stop turning away legitimate people.
Great!
Coinbase uses referral codes in their url..there are many other legitimate sites who do because word of mouth is the most efficient way of getting new users. Also It makes sense for a decentralized blockchain that users do their own marketing. And as the saying goes " there's no such thing as bad publicity", if people think it is spam or sponsors it doesn't matter because at least they will be aware of the site, something they wouldn't have been without the invite system.
Have you noticed that almost all crypto youtubers who post on steemit do not have a link to their steemit profil? This is because they have no incentives, with a referral system you can bet they will all put the link in the description of their videos.
One last thing, marketing is effectively sponsors spam, and to me a referral system is the best way to not give this impression, all other form of marketing are more offensive to users.
Most modern browsers don't really show any variables passed to the website through the url if it's after the question mark sign and you can also easily shorten your urls. It wouldn't be hard to implement referral tracking with a url shortener that could be built right withing steemit.com. I believe the benefits far outweigh the possible problems
On top of this, the fact that traffic to individual pieces of content from people not logged in (or even ones that are logged in?) has not bearing on the rewards means that people have zero incentive to share their steemit content outside the platform.