It's mystifying to me how someone could like Metallica and (presumably) DT, but then not like Iron Maiden.
I love, love, love me some symphonic progressive rock, 70's style. Really enjoy listening to Spock's Beard and The Flower Kings, especially the early catalogs of both of those groups. The first 6 Spock's Beard albums and the first....8 or 9 albums from The Flower Kings are prog gold to me. Same with Transatlantic. Now these bands ALL borrow very, very heavily from the styles, sounds and songwriting of 70's Yes, Genesis and ELP maybe even a bit of King Crimson.
So, you'd think that I would love or at least like Yes, Genesis, ELP and King Crimson right? Wrong! I like about 1/2 of the early Genesis albums but rarely listen to them. I can't name a single song by King Crimson, in fact. Wait, I lied, is "Thrack" a song? If so, it's the one song I can name from King Crimson. As for Yes, I don't own a single album of theirs nor would I. I find 95% of their material to be too tedious and I can only take so much of those elfen vocals by Jon Anderson. I know and even enjoy a handful of Yes tracks but that's it: a handful at best and mostly the radio hits like Roundabout, Leave It and Owner of a Lonely Heart. So, as a general principle I don't listen to any of those 4 bands, ever. Even though I love Spock's Beard and The Flower Kings, two bands who made a living by practically aping the Genesis and Yes early catalogs.
I love Dream Theater and Iron Maiden but have very little love for Metallica. I enjoy a couple of their classic albums, but I find most of their lyrics sound like they were written by a 15-year-old introverted sociopath.
I get what you're saying. A lot of Dream Theater fans do like Iron Maiden and Metallica, but there are plenty of people right here on this board that love Dream Theater but have little use for Iron Maiden. They're really not as similar as they might seem at first glance, especially lyrically, but also musically. There are similarities for sure, but I can definitely understand people liking Dream Theater but not liking Maiden or Metallica.