Aug 20, 2019 - 11:05 AM
First thing to recognize is Google won't usually admit to penalizing sites. To them, a penalty is usually assigned via a manual process in which their spam team reviews sites attempting manipulate rankings or visitor experiences via spam techniques, often in illegal ways or violations of their guidelines.
Examples might include cloaking, purchased links, malware, hacked sites, bait & switch techniques, and other more sophisticated attempts. In their eyes, an algorithm doesn't penalize sites.
However, to everyone else, any reduction in rankings or traffic versus similar competitors, especially when it happens suddenly or drastically, feels like a penalty. Maybe it is more appropriate to think of it as a filter in the algorithm that addresses something about your site that is holding it back from performing better.
The mobile friendly discussion is an interesting one. For about 5 years Google had been warning that mobile is very important and they will be judging sites by their mobile experience. They even set a date in 2015, many dubbed "Mobilegeddon" where we expected to see large fluctuation in rankings due to announced mobile factors to the algorithm. It turned out to be one of the smallest adjustments to the algorithm we've ever seen.
Then for years we received similar warnings, especially in leading up to the "mobile first indexing" launch in 2018 where instead of running two different indexes (one for desktop and one for mobile), we were going to see a consolidation to just the mobile index, where all sites would be primarily judged by their mobile experience.
What really ended up happening is that sites with really bad mobile experiences (super slow or completely unreadable) did tend to perform worse in mobile searches, but typically faired ok with their desktop searches. More recently sites with subpar mobile experiences often still show up in mobile, but their rankings may be a few spots lower than the same search performed on desktop.
With the majority of sites adjusting their mobile experiences in preparation for this switch, I'd often see the "mobile friendly" sites make mistakes that hurt their desktop rankings because they made it very "mobile friendly" but often hid or removed important content from the page.
Since your customers are almost entirely on desktop, it makes sense that mobile isn't a priority for you. However, if you've seen declines in traffic & rankings the past few years, that could be an indication that the site IS being judged by the mobile experience. Google often has a one-sized fit all approach, so B2B sites like your might be collateral damage in an effort to improve most searches.
So long story short, you should check your presence on mobile vs desktop to spot any differences in ranking.
If your site doesn't show up at all in mobile, then you definitely have a problem. If it is a little worse, then you should factor that into your ROI considerations. If it is the same, then you might be okay.
You can also sign up for Google Search Console to receive warnings about mobile, but keep in mind that Google has been issuing incorrect warnings for years now on mobile. If you already had this in place and received a message that your site has been moved to mobile first, then you are certainly being judged by your mobile experience.
BUT it also means that Google has determined your mobile experience is good enough -- the bigger worry for me in this case is if your mobile experience is missing text content because it will affect your desktop rankings in a negative way as well.
If I were you, I would work towards making your site work both on mobile & desktop, but try to keep as much of the functionality and text content on the mobile site as possible. I'm sure your customers might be in a pinch, travelling or something, and need to order something via their mobile phone. If it doesn't function, or is unusable, then you will be losing sales & potentially search traffic as well.