There is one big section of population that does not want to use any kind of supplements even whey to build muscle. Its a way of life for them just like how people stick to vegan foods.

Lets understand whey:

The human milk which the mom feeds the baby is rich in whey and has very little casein. But the cows milk we consume is predominantly casein and has very little whey.
Whey has the right proportion of amino acids that the human body needs and hence can be very beneficial for recovery and growth.
Whey is also very easy to digest and hence many people prefer it.

Whey protein is convenience and not a mandate:

If your profession needs long hours at work and you never know when you would be pulled in for work without breaks, then a protein shake can be super handy and prevent muscle loss and keeps you away from hunger.
Or if you are super busy that you run during breaks to the gym and finish a quick workout, then whey can be super helpful.
Even though they are quick absorbing, they have a downside too.. the amino acid spike created in your blood stream has a quick downfall within 30 mins where as solid protein lasts for about 6 hours .

Bodybuilding without whey:

I personally enjoy the taste of my whey protein and serves my sweet tooth. But if you wish to do it without supplements, then diet is your key.
We all know that the meaning of the word supplement is “bridging the gap in your diet” . So if you plan to eat 6 solid meals from sources like chicken, fish, steak, eggs etc and balance your fruits, veggies and carb sources… You can make the best body you could possibly achieve. Some of the best bodies in the past never had access to whey protein or any kind of supplements. The initial mass built by bodybuilders like Arnold, Sergio, bill pearl , Larry Scott etc was only through the natural food that they ate…

Note: – My personal recommendations post workout would be eggs for the speed at which they can digest