It might be more appropriate to say it was a government that made this choice. The French nation didn't get a say. Just like all other Western governments deciding to allow mass immigration, the people generally are opposed but never get a voice.
If the elites really wanted more people they could increase the incentives for domestics to have children.
Let's set aside the complexities of how governments are formed in a parliamentary system, and also ignore the subversion of representative government by lobbying. This is really simple: there was no vote on this in any western government. And in fact, political parties that explicitly oppose further mass immigration to Europe are gaining rapidly in popularity. But the governments actively subvert them. For example, there is talk of outright banning Alternative for Germany, a political party in Germany opposed to mass immigration.
So called left-wing parties now only care about Identity politics. They have abandoned the working classes.
Labeling something reductionist doesn't mean it's reductionist, nor magically make the argument go away like you desire.
What you're doing is a common propaganda technique used by tyrants and oppressive regimes to silence dissent with pseudo-intellectual discourse.
You should genuinely be embarrassed at this brain dead reply.
The same idea applies to the military-industrial complex in the US. Very few people are clamoring for further war. But neither major political party offers a legitimate alternative. There's no voting against it. Lobbying and direct monetary gain by the very top of society mean those in power want it, because they stand to gain personally, even if some recruit from a downtrodden town gets his legs blown off.
Likewise for mass immigration. The people in charge of major companies love reduced labor costs. And governments love increasing their tax base. They're the ones who get a say. Nobody else is even asked.