Mark, like other Viltrumites, trains, and gets more powerful with age. Beatings just hurt, they don't do anything for his powers.
Allen, on the other hand, works like a Dragon Ball Saiyan, getting significantly stronger after each beating (and the closer he gets to dying the stronger he comes back).
You're confusing Mark and Allen.
Mark, like other Viltrumites, trains, and gets more powerful with age. Beatings just hurt, they don't do anything for his powers.
Allen, on the other hand, works like a Dragon Ball Saiyan, getting significantly stronger after each beating (and the closer he gets to dying the stronger he comes back).
No, I'm not. It's the same for both. Just not so obvious early on for Mark. He ends up the strongest before he hits 40 because of this.