Rabbi Aryeh Lebowitz

In fact, Talmid Rabbein Yonah said that you don't have to have a makam within your shul because the entire shul is a makam kadosh and is therefore appropriate for a tefillah.

So there is the concept of a fourth issue is simply

that you want to use all the tools at your disposal to make your tefillah a better tefillah.

So davening in a place that is designated as a makkum tefillah lends a sense of kedushah to that place and elevates the tefillah.

If a person...

is davening in a place where they watch football games on Sundays, that is not a place of Kedusha.

In addition to that, I think we're up to reason number five, Rav Shechter points out that the source of Kedusha, the base of Knesset, is in Aron Kodesh, is Sefer Torah in the Aron Kodesh.

So you could fulfill Tzvila B'tzibra without an Aron Kodesh, and a room without an Aron Kodesh may have the Kedusha of a shul, according to some opinions at least,

You know, if you dive in there, but the full sense of standing before Hashem is only achieved in a room with both an Aron Kodesh and a Sefer Torah.

The Ramar writes in Siman Kufl Amal Aleph that you don't put your head down for Tachman in a place that has no Aron Kodesh or Sefer Torah.

And the Mishmur explains, it's from Apostle and Sefer Yeshua, that falling on one's face is only in front of the Aron Hashem.

In fact, Zilberstein in Chashuk HaChemit points out,

that the implication is that when there is a Sefer Torah present, the entire place is considered to be Lifnei Hashem, which means a greater sense of Hashem.

Another issue to keep in mind is that there are a number of environment issues when you are in someone's house, in a living room.

There could be a bathroom that's right there that is emitting a foul odor.

Certainly having a davening right next to a large screen TV and other paraphernalia

that a person has pictures all over the place.

You don't have photographs in a shul, because you're not supposed to daven even in front of begadim et suyarim, lest they distract your attention.

So there are tons and tons of distractions in people's homes.

Shuls are built to be places for tefillah.