I don’t think “Food crops cannot sustain the current human population” is the most accurate. I think adding on an “indefinitely” or something similar would be more accurate. The problem is that there’s plenty more land and resources that could go to crops, but it’s more of a problem of how sustainable it is long term.
Topsoil erosion could outpace soil conservation especially with synthetic fertilizer, but if people aren’t getting food now or in our lifetime then it’s not caused by an inability to grow enough crops. It’s caused by companies being driven by the profit motive. It’s more profitable to let food go to waste than get it to people who can’t afford it.
Currently the technology is there to make more than enough crops for everyone, but how sustainable that is in the long term is not something that has been a priority. If more effort is put into making factory farming actually sustainable, which is the way things are starting to go although pretty gradually, then the only thing stopping people from getting food is the incentive to destroy/ let it rot rather than take any potential loss from not artificially inflating prices