My previous company, it was mandatory to have all of your post-nominals on your business card, letterheads, e-mail signatures etc., as the company prided itself and traded on the qualifications, experience and abilities of its staff. Until our last MD took over.
As he had a huge ego & didn't have any qualifications (at all), except for an ability to convince our parent company that he was continuing the company a success and turning a profit, despite the evidence of our accounts & falling sales, we were all immediately banned from using the PNs and had to scrap any paperwork that had them. The overnight change cost the company thousands, emptied our order book & was the single biggest contributor to almost shutting us down.
My current company also trades on innovation, technology application & the training and experience of its people, but does not reveal any on any correspondence, e-mails or anything else that can be traced to an identifiable individual.
Although not military, we always have, and always will operate in some distinctly unpleasant and hazardous areas, so everyone's value to those who might want to do some AK47 fundraising is never available to the baddies, as even we don't know what our colleagues might have hidden after their names. Our Clients know the qualifications of the people working on their projects, but no-one knows exactly who on any given team has what.
It's worked for many years very successfully & we have had relatively few "incidents".
As in many things, it's not what you've got - it's what you do with them that is important & for what it's worth I'm an engineer & well on my way to completing my second row of P-N's, but very few people outside my immediate family and a couple of curious friends know just what I have. I only ever use mine when the self-impressed feel the need to start a p1$$ing contest.