IME certs are good for two things, novices who lack fundamentals and vendor partnerships (discounts and/or feature access that requires N certified devs/admins/etc.).

There's also the case where documentation is poor/nonexistent, but the vendor charges customers for 'training' and all of a sudden useful resources become available. I've always felt it's a weird way to treat _already_ paying customers, but seems common in the networking world.