Let us not forget that the United States Rifle calibre .30 Model of 1903 using the Model of 1906 cartridge was a project and product of the US GOVERNMENT. Therefore, almost by default, it was vastly superior to anything else ever made, anywhere, any time. (We will, of course, forget that $200,000 lawsuit -- paid in gold at $20 an ounce-- from Mauser..... something to do with patent infringements)
The M1917 was a far better rifle in every respect, but it was denigrated automatically by its "British" ancestry, even though the Brits were studying M1896 Boer Mausers, the Yanks studying Spanish 1893 Mausers which were very nearly identical. The 1917 then went on to serve 2/3 of Americans who actually got overseas, including through the period in which Springfield AND Rock Island BOTH were shut down over the exploding-Springfield fiasco. LOTS of details on this in Hatcher's Notebook!
As to the vastly-inferior Ross Mark III -- for which I found a NUMBER of supporters who USED them in the trenches -- we have to remember that less than half a million were built and that at least 60% of those were sent as aid to Mother Russia.... who ain't givin' them back because they LIKE them too much. Remaining British stocks of Rosses, the so-called "Weedon List" rifles, were used again by the Royal Navy and Royal Marines Light Infantry through the SECOND World War.... and then wholesaled to the Trade, which chopped them all down. Originals are SCARCE, especially in unmolested condition.... and there is STILL no other bolt rifle to equal them in many ways.
So there you have it: pure political propaganda on one side, actual experience in the face of political opposition on the other.
As usual, politics wins, but at least discerning collectors and shooters have figured out that the Ross was a FINE rifle.