It's very clever, but obnoxiously slow. It's useful for code golf and as a pretty impressive party trick. But like your banker will not be impressed with your college funding plan of pulling a quarter out of his ear, this is not going to make it in any real use.

Imagine naive absolute-beginner-programmer trial division. This is worse. Now add the overhead of counting via regex backtracking and integer comparison via matching strings. A fair number of regex engines will also start using enormous amounts of memory.

AKS is of theoretical interest, but not really a "normal test." It's very slow in practice, being beat by even decent trial division for 64-bit inputs (it's eventually faster, as expected, but it takes a while). But it is quickly faster than this exponential-time method. The regex is in another universe of time taken when compared to the methods typically used for general form inputs (e.g. pretests + Miller-Rabin or BPSW, with APR-CL or ECPP for proofs).

As others have noted, "has been popularized by Perl" is because it was created by Abigail, who is a well-known Perl programmer (though almost certainly a polyglot). It's also been brought up many times, though it's a nice new blog article. I hope the OP found something better when "researching the most efficient way to check if a number is prime." In general the answer is a hybrid of methods depending on the input size, form, input expectation, and language. The optimal method for a 16-bit input is different than for a 30k-digit input, for example.