Well wheat and rice have like under 4 gm of protein per 100gm. Vegetables are even less than this. I would have to eat kilos and kilos of stuff to meet my RDA this way.

That is why I promote replacing beef, the biggest problem with anything else. It isn't realistic to expect massive amounts of people to make such drastic changes to their diet in any reasonable time frame. We CAN drastically reduce GHG, especially methane from beef production by replacing it with a less harmful alternatives, and from there gradually scale back meat production as a whole.

Another issue is production. There needs to be time for food producers to change what they are producing. It takes time for plants to grow and animals to mature. If we all just ate rice and beans starting tomorrow, does the world even have enough to feed everyone? We can't just eat a bunch of corn like cows do. We would have to get corn farmers to grow something else.

Considering the nutrition and production hurdles, I promote just reducing beef consumption right now. If that ever succeeds, I'll move on to reducing meat consumption in general, giving time for viable alternatives to mature.