The whole idea of "certifications" is a relatively recent phenomenon, which would answer why it's growing. I suspect that hiring people with such things is the easy way out for personnel folks.
I don't really have to put up with certs, because I write embedded software, and there really aren't any certs for that.
Perhaps embedded "C" software doesn't count as "IT", but my background goes back to Cobol and banking software that certainly now constitutes "IT".
The certifications mania grows out of the CMM, CMMI and PMI mindsets that have KPAs for certifications and qualifications. Since it is a buyer market they can get away with it for now.