If you're looking for an answer to that question, have a look at this brilliant musical number crunching. Careful language use analysis of the term "alt rock" vs the term "indie rock" from the language use database otherwise known as Google.
All of this because of disagreement over whether "alt rock" and "indie rock" are really the same thing. They're not according to Google. "Alt" is an older term (nice german pun there) used more in connection with a certain 80s indendepndent style, whereas "indie" is the 90s "alt".

Incidentally, the whole website is good fun, even if I don't necessarily agree with the "older is better, rock is better" bias, among other good stuff tons of top 10 lists. In the list of 10 most overrated acts we find the following perfect description of what's wrong with your typical "the musicians musician" bands: "bad taste meets flawless professionalism".