Mbappe had threatened to grab the headlines again after just 21 seconds when he crashed an effort off the underside of the crossbar, but he was fairly reserved after that, having the fewest touches in the first half of any French outfield player.
The game had shades of France's 2022 quarter-final, when England kept Mbappe quiet, but Antoine Griezmann ran the show.
In Boston, Dembele was the ringmaster before taking his bow midway through the second half.
This was the first time he has scored more than once in a match for France - and his third goal was particularly special.
There were 17 passes before the hat-trick strike, the most in the build-up to a France goal at the World Cup on record, with all 11 players touching the ball.
Having taken a supporting role to his former PSG team-mate Mbappe in the opening two games, Dembele steered Les Bleus to three World Cup group wins for the first time since 1998 - when they hosted, and won, the tournament.
However, Stephan added it was premature at this stage to talk up this France side of going one step further than the beaten finalists in Qatar four years ago.
"This team is totally different to 2022," he said. "More than half the squad had never played a World Cup.
"We can only see as the World Cup goes on, then up our level as we play strong teams. There is the offensive and defensive side, we need to have that balance, and for that we need to wait."
Ultimately, the outcome to this final group tie was a case of differing managerial approaches. Norway needed a win to finish ahead of France but, with his selection, Solbakken showed he was satisfied with second place in the standings.
Fans will expect Haaland - who has four goals in this tournament, level with Mbappe - to return well rested when Norway enter the knockout stage next week, particularly after his replacement Jorgen Strand Larsen had a tame spot-kick saved by Maignan at the start of the second half.
Maignan is the first French goalkeeper to save a World Cup penalty, excluding shootouts, since Joel Bats in 1986. It caps the latest example of why his side are favourites for many to land a third title.