That's true. Every artist was influenced by another at some point. Unless they lived in a hole their entire life, there's no getting around that. No matter how original you think you are, you were influenced by someone.
I don't think there's anything wrong with learning from other artists though. That's what you do, it's how we learn. That's why we do "study's" in drawing class, because you can get a lot more out of a drawing by recreating it than you would looking at it. You can work through it and try to see how the artist might have approached it.
I've definitely taken a lot from Takeshi Obata. His work in "Platinum End" really inspired me to up my game in hair detail.

I did a few sketch studies, and then I gradually started incorporating detailed hair in my comic. Eventually it became a natural inking style for me, and it greatly benefited my comic, especially in moments like this:

Sometimes when I'm having trouble drawing a good enough face, I'll sketch his characters' expressions.

By the end of the day, I still draw my characters with my eye style and I'll make up my own expressions in my final drafts. The Obata eye study kind of works like stretching, helps me expand my options on how to approach my drawing in ways I didn't think about. I don't feel like I'm "copying" him. You may be able to see his influence in my work, but it's still done in my own style.
Professionals have done this too. I don't know if you know Mark Crilley, but he did a lot of Obata studies to help find a more serious style that worked for his series "Brody's Ghost" The designs for his main characters were a lot more cartoony before he did Obata studies.
This is even how music works too. I've watched a lot of documentary's for some of my favorite metal bands, and they all talked about how in the beginning they "stole" techniques from some of their favorite bands to help them get started, but they didn't want to sound JUST like them. Learning their techniques helped them improve and create their own style. Hell, one of Metal Hammer's issues last year came with a CD of all the bands that Metallica took influence from. Freak'n Metallica. They're one of the biggest bands in the industry right now.
I used to take an ear training class in college, and we would listen to Jazz tracks and immediately be able to tell who they took from "Oh yeah, you can tell he listens to a lot of Miles Davis- Oh, he just did a classic Louis Armstrong riff right there, nice". Not that surprising, because this is what artists do. Taking what they see or hear, and incorporating it in their own way.