I've been reading articles about church buildings that have been discovered prior to 313 AD. Yet, many of the articles cite that "scholars" reject them because there "weren't organized church buildings prior to the legalization of Christianity".
They cite that all previous churches were house churches, martyriums or catacomb churches. What I want to know, is what is so unheard of about organized churches prior to Christianity's legalization?
It's unheard of because it goes against secular and Christian paradigms and many historians don't want to be labeled as crackpots?

I actually am not aware that all or even most historians take the point of view that public places of worship for Christians could not have existed prior to 313. However it does seem that as a general rule it is safe to say that public Church buildings did not exist, for about a zillion reasons.
Isn't it natural that a group used to worshiping in the Temple and Synagogues (that also have a structure with Deacons & Bishops, later Priests) tend to form their own places of worship, even under persecution?
They did form their own places of worship; house Churches.

House Churches in the ancient world were not like worshipping in your living room though. They were dedicated spaces set aside and turned into "chapels" basically. They more or less looked like a Church, but were part of a house. A modern example would be like turning one's garage, or a spare bedroom into a chapel for Christians to gather together and worship. These rooms were set aside as Churches, but were part of a private individual's home. This is actually true of many first century Synagogues in Palestine too which were not stand alone buildings, but often a wing of the village Rabbi's house.
Not to mention that there would definitely be some places where Churches could have been formed because it wasn't like Christians were constantly being hunted down everywhere. (we know some Governors or Romans favored Christians and protected them)
Where would an illegal religion (even though it typically wasn't persecuted) get the money to build Churches like we think of today? Renovating a spare wing of a senator's home is one thing, building an entirely new structure is something quite different. To do so as a public place of worship, (as all religious temples in ancient Rome were public places of worship) seems likely to be an extremely rare event if it occurred at all. How could Christians have "kicked out" the Pagans if a public place of worship actually existed? The ancient world viewed religion very differently, and ancient Christianity viewed religion very differently than we do.
What basis do they have saying that no church buildings could possibly exist prior to 313? It almost seems like that is a scholar/historian form of a "fundamentalism". I would have figured they would be open to the possibility of an existence of organized churches, unless they have other motives in mind...
I'd like to see what article you're looking at specifically. I'm not sure there is this mass rejection of stand alone Christian Churches prior to Constantine that you've come across. I know there is a Church in Megiddo Israel which dates to the 3rd century, which at least appears to be a public shrine....dedicated to "the god Jesus Christ", sounds awfully pagan to me. So in some ways if scholars are rejecting this particular Church (I believe it is the only one in the Roman Empire that appears to be a stand alone Church prior to Constantine) they are likely doing it to protect Christianity actually. For if we take this Church at face value, it makes Jesus to be just one god among many and that goes against all sorts of paradigms doesn't it?
The question you raise is an interesting one, however historians cannot just assume that Constantinian styled Churches existed prior to Constantine as this goes against all the evidence that we actually have. Even the New Testament and the Church fathers tell us about worshipping on the homes of wealthy Christians. Perhaps on the fringe of the Empire or outside the Empire things were different, but I think historians generally have a good take on this issue. If stand alone Churches did exist where are they? However the answer really does depend on what one means by "Church"? Do you mean cathedrals? clearly these simply didn't exist. But I've seen pictures of these house Churches, and they do look like, well a Church. They aren't just some guys living room or game room, they had baptistries, icons, mosaics and altars. These are just as much a "Church" as a stand alone building that was begun by Constantine. However if you have the article you're refering to I'd to look at it. I don't think it's any sort of universally accepted idea among archaeologists and scholars that stand alone Churches could not have existed. If someone is saying that I think they are being misleading, even if it is by accident. Fun topic though, as I find Christian origins utterly fascinating.
NP