I imagine that too many new users on one day is a troublesome idea regardless of what site they’re from or why they arrive here.
It’s as simple as noting that new users are new and still learning from everyone else around them. When everybody is new, it’s hard to get a feel for the current culture and style.
I imagine that it would probably work on a permanent basis to gate new accounts to a certain fixed value per day or proportion of new to old accounts, e.g. .1% per day or whatever.
Personally, I came here from Reddit 1,791 days ago, so I will be the first to say that I hope we don’t have an “anti-Redditor refugee” policy, whether express or implied. Far better to demonstrate through action and voting what we value as a culture and welcome as many people to the site as we can handle without diluting our ability to teach by example.