I think it's worth noting that many of the "incomplete" proteins actually have all the amino acids, just one of them is relatively low. If you are varying your protein sources at all and eating more than the recommended quantity of protein from WHO studies, it would actually be hard to be protein deficient. Take pea protein for example. It's slightly short on methionine/cysteine, but not by much. If you just get some extra pea protein, you're good. You wouldn't need any other protein sources, but you'll pick those up with other foods incidentally anyway.
In the medical sense, the only time people are diagnosed with protein calorie deficiency is in the setting of starvation or chronic disease. If you are eating enough, you exercise, and you are under 60 years old, completeness of proteins isn't important in my opinion.
Does more protein help exercise recovery? Yeah maybe, but you won't be sick or feel bad without it.
One of my first mentors as a nurse was this old battle axe who had been around in the ER for decades. Tough as nails, hard as a rock. She was pushing morphine in some young girl's IV. This girl was maybe 18 years old and having a good amount of pain, nothing crazy but needing medication. She was really anxious about it. She foolishly asked the question, "What's the worst that could happen?" The nurse answered, "You could die." No expression or sympathy or care. And she just kept on slowly pushing the morphine without another word as the patient visibly tried to suppress her terror.