[boredtofears]

In my experience coming in as the new guy with X many more years of experience doesn't automatically mean you're going to be listened to no matter how "assertive" you are. Communicating assertively can easily cause others (especially newer devs) to be on the defensive. If a whole team has decided on a trajectory you're not likely to change things very quickly by just exuding confidence. You don't have much "social capital" on a brand new team until you've demonstrated your skillset.

Also I find the habit of passing judgment of a person on an internet forum extremely distasteful and pretty disingenuous - you don't know enough about this person from a two sentence forum comment to judge their communication/persuasion skillset. It does nothing to support your argument or do anything other than make you feel superior to that person.