You have to remember steam reviews are a minority of the playerbase. You're using steam reviews like they depict the opinions of all customers, while only few actually write them. You can say, based on that data, that out of all that have left reviews, Solasta has overall higher satisfaction. Not the same thing as all customers.
Also, that's only counting the ratio of recommend / not recommend. You could be extremely satisfied or only somewhat satisfied and both translate to being the same value, a recommendation. While the correlation is there, it is not an accurate measurement of customer satisfaction. If the difference was 30% vs 70% then yeah probably the 70% game is doing something better, but 87% vs 93% during early stages of EA really doesn't tell me anything.
And if we're arguing based on this if following 5e rules closer is better, it tells us even less. Did they write the review based on that, or maybe story, soundtrack, visuals, etc played a bigger role? Or maybe they had lots of bugs/crashes?
I'm not here arguing that BG3 is better than Solasta, I wouldn't even know. I'm just saying that difference in steam reviews is not undeniable proof that Solasta customers are all in all more satisfied like you said
