Its quite common when defending Martial to downplay Lukaku. Probably because Martial is perceived as skill full and technical, while Lukaku has a shite first touch and is outperforming him which doesn't fit into the view of football a lot of fans have (where they massively overrate what players do on the ball).
Lukaku was not streaky, his overall game has been consistently improving as the season went on. The only thing streaky was his goal output, which was because of the shocking service he got when Pogba was out injured. He isn't Ronaldo or Messi, he is reliant on getting the ball in dangerous areas.
Lukaku, Sanchez and Lingard all play with bravery and freedom.
Alexis Sanchez: "We need those kind of demands to get the best out of us. He asks me to play a free role, to enjoy myself, to attack, defend, to do everything!"
You are wrong, but I'm sure you'll ignore words from the players themselves and stick your head in the sand.