Experienced gamblers can have higher chance to get "guaranteed" profit than newbie, non-experienced gamblers, as always true in anything.
Valid point. Most gamblers are newbies who don't know much about RTP and other technical stuff and just proceed to play wherever they want without thinking too much which is why this RTP promo wouldn't really pique their interest.
On the other hand, it would definitely pique the interest of experienced gamblers like me who would try taking full advantage of it.
When I first started gambling, everyone was promoting 1% house edge dice, so I immediately learnt about house edge and later I learnt about RTP when crypto casinos added slots on their websites. I don't know if there are still players who don't know about RTP but I can say that Metawin is a huge promoter of RTP, they have slots with the guaranteed highest RTP.
From a user experience standpoint, they have RTP and Volatility under the image of every game, so it should be intuitive for every player to click on each of them and when they click on them, a popup appears that explains what RTP and Volatility and what they mean under each game.