Well, depending on where you have silk it may serve some mechanical function as suggested in this blog post from a UK string enterprise, helping the grip on tuning posts and also serving as a wear-and-tear buffer on same:
Why do we have silk on our strings? | Strings DirectStrings Direct.
I worked in the industry. There are a lot of bass strings without wraps but I definitely get that strings could wear tuning posts. However, the industry never expected “tuner post wear” with guitar strings. This is because bass guitar’s origin is the bass violin.
Guitar strings don’t have wraps. Do guitar tuners have different physical properties? I play guitar and baritone. I can get bari strings up to .080 gauge, that’s like a bass guitar A string. But they aren’t wrapped ever.
But getting back on track, D’Addario and Ernie Ball, Warwick, Elixer, DR, Mangan, Stringjoy, all have made round wound bass strings without silks. These aren’t discount off-brands.
I’m just saying, sometimes manufacturers tell you what their marketing managers tell them to say. And silk on bass strings is branding.
Also, knowing from physics that the friction at the post is equal to the friction at the saddle (and is not distributed around the entire saddle so the local contact is higher) does it really make sense that some brands would silk the leads but not silk the ball ends? Is it at all within reason that the extra cost of wrapping a part that might be completely invisible (through body?) is less profitable?
The “mechanics” answer has too many gaps to be a reasonable answer.
When in doubt always follow the marketing. And remember that by definition most product engineers and product managers fall under the marketing umbrella. Sometimes employees say what they are told to say.
And last but not least, tell your Rotosound guy that Rotosound 45 NPS bass round wound strings do not have silk. They’re marketed as the same string as 66 but without silks to save a couple bucks.