Lots of nations were fighting smaller wars as well and more of them than the United States and yet none of them devolved down from Company to individual fireteams as the manoeuvre unit before 'Wipers'
As I understand it, the primary reason is that the ‘modern system’ is terribly expensive to implement and very challenging to use. You have to not only train every NCO to command the type of small-unit tactics that you’d previously only train company commanders in, train the company commanders to manage semi-autonomous minor units rather than blocks of obedient proles, but also train
everyone to deal with a battlefield where every unit is by intention virtually invisible and moving unpredictably, etc. etc. It’s very difficult and even today lots of armies haven’t managed it.
Of course, when obliteration by modern firepower becomes an issue its extremely attractive but then runs into practical problems, namely that multi-million man armies need vast numbers of NCOs and officers to receive this complex small-unit training at the exact same time when millions of recruits urgently need to be trained how to hold a rifle and tens of thousands of officer trainees are struggling to hurriedly learn map reading and whistle blowing.
OTL that put everyone into a situation of having huge rapidly expanded armies that were tactically clumsy for a while, in both world wars.
All this to say that though it is not impossible that fully automatic 1907's with bayonets were issued to assault troops during WW1, I am a little skeptical as the primary evidence seems spotty.
At this point the French Army ground use select-fire 1907 is more a religious discussion than history, IMO. The true believers refuse to countenance any interpretation other than that word of mouth has somehow passed on the true facts for a hundred years despite no physical evidence having survived. The sceptics similarly refuse to believe that all the rifles and all the documents could have disappeared in only two world wars, two demobilisations, one Great Depression and one foreign occupation.
Fortunately it doesn’t really seem to matter, since either they never existed or else they did and were so amazingly nondescript that the French army (home of the chauchat, ribeyrolle, RSC) retained
literally not a single written sentence about them. Either way I think they can be ignored as utterly irrelevant.