they don't really need this detailed info, but it feels contrived to be secretive.
They don't need it, so you shouldn't supply it.
Even if they do 'need' it, it probably isn't your place to reveal this.
Don't feel bad, your suppliers will (should) know this, and won't (should not) be offended if they find out (or figure it out).
This is how the game is played.
As an example: if you know someone in a different softball league (who your team will never play) you don't discuss your secret signs with them... just because.
Is there any harm with telling suppliers what tech we use and why?
A possible harm is that it could have an effect on the support your company gets. Not very ethical... but I've seen it happen.
Here's an unrelated example, that demonstrates how leaking information can be detrimental to a company in a way that wasn't expected:
I worked at a company owned by a guy who we will call Jim.
Jim's company mostly installed this one phone from this one supplier in Texas.
This supplier sold phone systems across the US to other companies like Jim's company. Jim was one of their bigger customers (selling a few hundred phones per month).
One day the president of the supplier flew in for a meeting with Jim. At the meeting he told Jim what the new phones were like, and showed pictures to see if he liked them. Jim asked for a couple of the new phone and the supplier's president said, "We don't have any yet. We are retooling our production lines from the old phones to the new ones."
This told Jim that there was a limited supply of gray phones and the new white ones wouldn't be available until the lines were retooled (months).
As soon as the supplier's president was out the door Jim called his procurement person and said, "Order 10,000 phones from [company]. If they say you can't have 10,000 order as many as they will let you order and let me know. I'll call back and ask why we can't have more."
Soon after that (a month?) the supplier didn't have any phones for the rest of his US customers... and it was almost a year before the new phone arrived.
Leaking information, even if you are authorized, can have terrible consequences for a business.
Jim's company offered the old gray phones several years after this event, along with the new white ones!
Does that help you think about things differently?
Unintended/unexpected consequences are a real thing.