I would certainly hope a player who played more games and took 500 more shots in his first 6 seasons would have more goals.
10 more goals on 557 more shots for some context.
And we don't have to imagine how Matthew Tkachuk would have done on his next 500 shots. He scored 40 goals (not 10 goals) on 324 shots which is better than Brady Tkachuk's career year and a better 82 game pace than what Brady Tkachuk is doing right now.
What would other Ottawa players have done if those 557 shots were distributed among Stutzle, Batherson, Norris, Giroux, DeBrincat and others? I think it's very fair to question what this team would look like if Brady Tkachuk took fewer shots and was closer to players like Matthew Tkachuk and Jamie Benn with his shot selection where he still takes a large amount but he's not Top 5 for the time period of his career with elite superstars such as MacKinnon, Pastrnak and Matthews.
Everyone seems to be taking the default approach of "oh the team would be worse". I'm not convinced.