Never mind the fact that for well over a decade, free prospects regularly turned into sales with no smoke, mirrors, first born or cash payments required. The real problem is that there are far fewer "free" prospects on the "free" internet. It's fully owned.
First, change happens. Suck it up. And deal with it.
Second, one needs to stop identifying the internet with Google. The internet is far far more than the web, which, in turn, is far far more than Google. The Google is 'all' mindset is certainly a common delusion however it's commonality does not negate the delusion. Yes, once upon a time it was the easiest. So easy that everyone climbed on board and easy became crowded.
Third, one needs to stop extrapolating from the specific (one to many search queries have pushed non-enterprise organic results well down the listings - something that has been increasing for a decade and should NOT be a surprise) with the general; internet traffic is still largely free (although in some niches arbitrage plays are easier) and acquiring that free traffic is certainly not 'fully owned' (although platforms are increasingly preempting where they can). Adapt, for crikey's sake! Surely a decades continuing notice of change is sufficient lead time?
Fourth, bots have multiplied. Bots coming via SEs including Google is through the roof. If one doesn't account or block for this one's analytics analysis is fundamentally flawed. Just because one's traffic is almost all via Google doesn't mean that it's necessarily anywhere near all human.
Fifth, traffic patterns tend to be unique by data centre. This used to be much more visible in the long ago when one could see update progression in real time and before the noise of personalisation became overwhelming.
Sixth, how/where SEs, including Google direct traffic has changed what with Navigational/Informational/Transactional/Personal/Local/etc. Given the volumes even the smallest misdirection is huge in absolute numbers.
Seventh... well, there is a lot that most webdevs never contemplate nor SEOs for that matter. There are a lot of trees in the forest and I think far far too many are more lost than I. They just don't know it.
Yes, I am fortunate to have begun in the long ago when 'life' was easier. However, even then there were a significant number of similar complaints about traffic, conversion, Google et al. Yes, I am 'fortunate' to have kept 'adapting', adding features, adjusting layouts, etc. mostly for solid business requirements but also because it's fun!
I have the wherewithal to go deep into data analysis and marketing and leverage machine learning. But while I am playing where few webdevs have the opportunity the questions I'm asking can all be answered, to some good degree of workability, without all the bells and whistles. The wealth of free advice that would have and still can guide one past the shoals of Google change, into diversification of traffic and revenue et al here at WebmasterWorld is absolutely priceless. The biggest secret of success on the web is that there is no secret.
Perhaps the best advice one can give is RTFM.
Then test. And adapt, always adapt.
Be ahead of the curve rather than behind.
The road is always moving, standing still means being passed right on by.