It's been around for a while, but note that it really only stands out to those that have a use for it.
I'd imagine that a pretty large percentage of users only really use one domain.
Then, if you add in the ones that simply redirect other name variations or TLDs back to their main domain, they're not exactly burning up the resources.
It just depends on what you need. There are plenty of features here where adding "unlimited" before them wouldn't affect my usage.
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