[tialaramex]

I'd say that more often than not people building this sort of stuff in-house have no idea what they're doing. So although that part of the design doesn't make much sense it's not astonishing to see it.

A PKI provides a deeply technical solution to a hard problem you probably don't have. This technology is most often deployed when somebody has a different, easy problem, but they don't like the relatively easy non-technical solution.