I think the point about the competition not being as strong is the most important one. But in 2015 I'm not sure having two-three massive tactical missteps would have put them in good position in their group. In 2015 they drew Sweden and beat Australia and Nigeria in group play. They may not have made it out of the group, or if they had finished second instead of first they would have faced Japan in the first knockout stage instead of the final.

In 2019 I'm not sure they would have even been able to beat Spain in the first knockout stage, much less England in the semifinals.

They could certainly have beaten Netherlands in the finals, though--2019 Netherlands were luck the US didn't score 4, 5 or 6 goals, it was a very lopsided match.

This is just for fun. Go back in time and replace the 2015 and 2019 USWNT in the World Cup with the 2023 USWNT. Would the 2023 team win the World Cup is those years?

I think they would. The 2023 team is more athletic(faster) and technically skilled vs those teams. The competition was not nearly as strong.