>>>Diogenes Laertius lived about three hundred years before the gemara that gives us the version that is now in our siddurim
This is of course plagrized from an apikorsus blog.
The Tosefta which first mentions making those brochas predates Diogenes Laertius.
The reliability of Diogenes’ sources has been questioned, even by secular scholars . Do you believe Diogenes Laërtius claim that when Diogenes of Sinope committed suicide he held his breath for a few days until he died? Or do you go with the teretz that he had several breath holding sessions until he caused himself enough brain damage that he died? Even the believers who give that answer are clearly saying that not everything coming from Diogenes Laertius is to be taken at face value. And in this case he himself explicitly says that his source is just hearsay ( hundred of years later)
In general the sentiment found among academics that if the Torah says something but that sentiment is also found by non-Jews of the time there must have been some non-Jewish influence is nonsense. Some sentiments are universally believed at least at certain times. The fact that Torah and lhavidl say some Greek philosopher both said a similar concept just shows that the idea resonated even in other cultures. Not influence ch’v