Is there some certification for this, or is it just another part of being a webmaster? This mitigation skill does not seem to be very widespread, or am I incorrect?
It's just another part of being a webmaster.
It is not even narrowly spread, imo; more like waved vaguely in the general direction of...
...if the market is unwilling to pay for such a service, I wonder if the problem is a lack of understanding/communicating the benefits or the lack of need for such a service?
1. many webdevs are not only unwilling but often unable to pay for pretty much any service.
2. many webdevs are technically incapable of much beyond cut-n-paste 'coding'.
3. webdev denial about traffic quality (including percentage of bots) is as great as that about content quality.
4. given the ad premium I can charge for 'clean' traffic some advertisers are understanding, however I've been banging the drum for over a decade now and it ofttimes felt - feels - like I am beating my head against a brick wall.
I still get told that 'they' can get ad space far cheaper just about everywhere else - the ad variation of my nephew can build a site for far less... too many chase price rather than value, which means ipso facto that they don't get, refuse to see benefit. In all my years of business, both B&M and online I've always been amazed at how many willfully ignorant, niche/business incompetent folk manage to make a success of it.
As mentioned previously Bill Atchison aka incredibill, who recently passed, had been working, years ago, on a commercial bot defence program. Unfortunately, ill health put an end to it's development. Given my experiences developing and maintaining one for my sites (with significant in/direct help from Bill) I believe that the combination of effective, simple, easy, customisable, and inexpensive may be several goals too far.
These aren't the droids we're looking for.
Are we providing a solution to a problem that need not be fixed?
You can go about your business.
Move along... move along.
What happens when the vast majority of sites' traffic is dirty is that advertisers adjust their pricing accordingly. A quick rule of thumb for most SME sites is that at least half their traffic is bots. It can exceed 90%. And that is why most third party content/display ads are so cheap. The marketplace has discounted them. So, if you are wholly invested in third party ad network revenue going to the trouble of 'cleaning' out the bots may have a negative ROI. Your traffic is a better deal but unless that becomes known and advertisers whitelist your site your revenue per remains bog standard but now with less traffic so overall down accordingly.
If you are doing affiliate marketing and/or you are or plan to sell ad space directly then it is well worth doing. Another benefit feature. That needs to be demonstrated and sold.
All that aside, bouncing bots has, as also previously mentioned, the benefits of lowering server connection and bandwidth overhead, decreasing potential scraping, malware infestation, and other nasties. Basically it's the online equivalent of mitigating graffiti, vandalism, shoplifting, robbery... nah, no reason to do any of that!
Is my time better spent learning to juggle?
Once a webdev always a juggler.