The SBC's member-churches (not referring to the entirety of churches that identify as Baptist) have been dwindling for the past decade or two.
The number of people who are members of a "SBC-affiliated" church started dropping in 2006, and hasn't swung that trajectory back in the other direction since.
Being a "religious outsider", I see this two ways.
I'll take religion out of it, and just treat it like any other ideologically driven group that's based on a core set of principles and bylaws.
A) On one hand, as times and demographics and attitudes change, rigid adherence to certain rules is certainly going to come at the cost of membership numbers if certain attitudes in the general public are changing with each iteration of "population recycling" (a "nice way" of saying "when older people die, and younger people take their place")
B) on the other hand, Even if social attitudes are changing, an ideological organization understandably wouldn't want to break from too many of their principles and bylaws. If they did that too much (and bent to public attitudes on everything), then the whole thing just becomes a weekly generic social gathering... in which case, if the only thing you have in common with the people in the group are that you call go to the same building once a week and hang out for an hour (and ideas are all over the place apart from that), then what's the point?
To use a non-religious analogy.
Say there was an animal rights/vegan organization (like PETA)... They have it written as one of their core rules that their member chapter leaders aren't allowed to consume any animal products.
Demographics change in the <insert region here> part of the country, and people in those areas start redefining the term "vegan" to include vegetarians, pescatarians, and people who eat plant-based 6 days a week, but then give themselves a cheat day where they can consume some dairy.
To accommodate the changing attitudes of the regions they're in, and keep their local chapter membership numbers higher (without regard for the "parent org", they start allowing people who are pescatarians and "dairy once a week" to hold leadership positions in the chapter.
I could see why the parent org might want to say "no, I don't care if the popular opinion in Green Bay Wisconsin think is "it's still vegan if you only eat cheese once in a while... that's not what our bylaws say, and you shouldn't have leaders serving occasional cheese sticks during gatherings"
To put it in consumerist terms, each denomination is a "brand", they each have their own distinct rules and interpretations. If you go down the path of watering them all down to the point where they all accept everything and bend to every notion of "inclusion", then every church becomes Unitarian in theory. "Come in, believe whatever you want...or don't... just grab some food and socialize for an hour" isn't a religion anymore, it's more like an office summer picnic.
