I have some experience in this world, many years ago. You are correct that there is no “IFB” denomination, per se. However, Independent Fundamental Baptists pride themselves on the whole “we’re unique, just like everyone else” nonsense. They proclaim their independence and look down upon denominations with hierarchy, but then they turn around and have their own colleges, media (print, digital, audio), conferences, musical artists & groups, regional organizations with hierarchical leadership, in-group superstars, and so on. They’re a loosely-held, tightly enforced group-that-isn’t sort of a group. They have their own standards & practices that are common to the group. They have reciprocal recognition agreements (usually couched in terms of “churches of like faith & practice”) with each other.
What’s worse, IFB churches serve as a protective collective for preachers run out of a church for sexual impropriety (regardless of age), as there’s an unwritten agreement that any “issues” at a prior church won’t be spoken about or mentioned when a preacher is looking to hire on at a new church. It’s a “he’s not our problem any more, we made the victims apologize, we dare not ‘speak ill of God’s man’, etc…” mindset. So, predators are free to move about and very rarely does word of their misdeeds make it outside of the church where the incident(s) happened.
Yes, there are various levels of “crazy” that sub-groups within the IFB world adhere to. As you might expect with a system with so much “independence” there is infighting and cliquishness (“we’re true believers, and you’re not, because we believe XYZ and you only believe XYZ, so we won’t ‘fellowship’ with you any more”). But when push comes to shove they circle the wagons and defend their own, since it’s them vs. the big scary evil world.
The IFB exhibits the essential characteristics of a denomination. This is abundantly clear to anyone who has been on the inside of that world. After so many claims from various elements within the IFB sphere that they’re not part of any network of churches or organizations, it became common to refer to them as a notwork. The only ones who think that IFB types aren’t a denomination, group, collective, network, whatever-you-want-to-call-it, are the IFB themselves because “independence” is prized higher than anything else, including ethics, morals, and general-purpose humanity.