All the examples that you say are quite old. What huge propaganda campaign is going on underhandedly in 2019?
-Lots of relentless propaganda trying to differentiate and demonize political parties (liberals/democrats bad and hate america!) when in reality there's not much difference between mainstream elements of both parties outside of wedge issues.
-Lots of green-washing propaganda (consuming product X is good for the environment)
Also, both of these are "industry trends", where I think what the parent is asking for are campaigns unique to a single company and a single advertising agency, but with far-reaching effects on public perception beyond that company's brand.
The campaign has successfully instilled a few formulas in the public opinion- for example:
1) that Israel has a right to defend itself; (notice how subtly it shifts the issue from that of whether it is defending or attacking, to whether it has a right to defend itself from attacks).
2) that Israel's right to exist needs to be constantly reiterated. (Which implicitly suggests that it's possible the speaker doesn't recognize it- you don't ask somebody who criticizes France to declare it has a right to exist).
3) that the reason Israel is attacked is hatred and anti-Semitism. (And not, of course, that it is violation of international legality and human rights).
4) that there is no meaningful distinction between USA's objectives and Israel's. (While Israel and USA are separate countries and by nature have different objectives).
Some less official but widespread ideas are the negation of Palestinians existence (they are just Arabs) and a "might makes right" principle ("Palestinians have lost and should get over with it").
Intermittent fasting seems similar at the moment. Promising results, and I can't find a sponsor. Sure, given any trend, people will find a way to make a profit. But the kernel of these seems fairly organic, unlike say, the "South Beach Diet."
To ericb's point—there's a massive difference between a profit motive of selling optional advice versus selling the "product". Like many real diets, keto is little more than a subset of foods already available at the supermarket. It's not like someone was trying to flog a special powder or vitamin pills.
I case you're wondering, this "hydration" thing basically is a scam too, just like keto. Fun fact: it's generally impossible to die of dehydration, unless you genuinely don't have access to freshwater. People will drink when they're thirsty. No athletes have ever died of it. However, a significant number of athletes have died of over-hydration (water poisoning). Just like keto, it's dangerous and unhealthy.
Your level of unqualified certainty about keto diets is amusing. I personally know a number of people who are sticking to that diet and they've all had their health objectively improve as a result. (Weight, body tone, lipoprotein subfractions.)
In one case, he had chronic fatigue that his GP (family doctor) couldn't resolve, nor two expert referrals who tried medications and special diets. The keto diet led to an effective cure (the key factor was narrowed to the consumption of sugar, even relatively small amounts) and when combined with other health marker improvements, now considers his keto diet as necessary for a tolerable existence.
So yeah, dangerous and unhealthy.
(And for the record I've no idea what "this hydration thing" is. When I cited hydration I wasn't talking about some special diet, only to the basic concept of not being dehydrated.)