It is an environmental problem because the resources required to obtain the same caloric/nutritional content from meat is far higher than the alternatives. If the "better method" is better than our current method of meat production but still too intensive to maintain at scale then it doesn't solve the problem without reducing the scale of meat consumption.

That doesn't mean nobody can eat meat, it just means that on average people need to eat LESS meat.

Why are you so against people eating less meat? Your arguments here are akin to the "nuclear energy" bros who rag on renewables all day. Just like we can use renewables and rely on nuclear to fill any gaps, we can lessen meat consumption and rely on less intensive forms of meat production to fill the gaps.