Arianespace had the lead and lost it, because it kept the old way of doing things. Or are you arguing Ariane 5 was technically behind and wasn't competitive in the '00s?
Ariane 6 is not that far behind the other "old space" companies, which the US is struggling to keep around as alternatives to SpaceX. It's not like Boeing and ULA are doing much better.
We should be critical of Arianespace, and find ways to get it to improve, but just throwing everything at SpaceX will do nothing to keep them honest.