As to the basic question posted here ---since "fundamentalism" is interpretive, we would be left to useless debates, so the real question might be such as: Is
Bible-only enough? That, of course will also be debated by mis-interpretations of various Bible verses, but at least it is on more solid ground, would you say?
For those who truly want a Bible-only fellowship, they will look for a gathering worldwide which holds to "no schism in the body" universal (1 Cor. 12:25) as God enjoins us. I submit that there is such a fellowship from that revival in 1827 AD, where it appears clear to some of us that God set about to recover Church truth as He ordained from that revival of the Gospel in 1400 - 1500 AD; which freed saints from the tyranny of the RC religion.
Since saints were mostly without literacy and the written Word, they copied much of the rituals, hierarchy, programs, ceremonies, rules, etc. which they had learned over a thousand years of RCR rule. Thank God for His continued work to recover
Church Truth in circa 1800 AD. One can read much about all this work at the site:
www.biblecounsel.homestead.com and ask questions there for further study and prayer, and where such gatherings might be today. Look up always, for God cares for His own always!