That's a valid point on the variety, or lack thereof, of semi-auto rifles. Before the R1 there was the BAR and 7400 and that was pretty much it going back for quite a few years.
The 7400 was never made to handle magnum rounds and thus would probably be suspect with hot long action rounds. The BAR was made to handle magnum rounds and thus should be able to handle moderately hot factory rounds but seeing as there are probably 4 7400's out there for every BAR, it wouldn't make a lot of sense for Federal or whomever to point out only one type of semi-auto as possibly being useable especially when Federal had no control over Browning suddenly changing specifications. Better to leave the liability to the rifle manufacturer and buyer.
I have a 7400 in 30/06 and it is a tempermental rifle when it comes to loads. I also have a BAR in .270 and you can pretty much run any factory round through it within reason. The quality difference between the two is quite apparent as is the R1 to the 7400 but seeing as 7400's are nearly 1/2 to 1/3 the cost, what can you say.
This is just an hypothesis on my part, but I would be willing to bet that an R1 and BAR can handle hot factory versions of 30/06 just fine considering they don't exactly change a whole lot in there .300 WM versions.