i think i would respond better to an engine maker saying this if it wasnt coming from the Renault camp...i have lingering issues with how they have handled their branding over the last decade so am a tad cynical when it comes to this manu.
as to your question though...for me, its a bit like Adidas saying that the World cup should be about Adidas because they are the ones who provide the balls and you cant play the game without balls.
as you say, if Renault or the other engine manus were not there then the the teams would just use a stock part/equipment as a replacement and the game would go on.
so in an existential sense, there is an element of absurdity in suggesting that the equipment should be the most important aspect of sport. for me its not more important than the athletes and not more important than the teams who organize the competition.
i am reminded of a Michael Jordan/Nike commercial where Spike Lee claimed that 'it's gotta be the shoes' when describing MJ's prowess.
https://www.youtube.com/watch?v=Abr_LU822rQ
a great ad and no doubt helped to sell a lot of shoes but the reality is that it doesnt explain why some athletes (and teams) are worth watching and supporting.