Which is why much of the Church retains the practice of Daily Mass; but when Scripture makes a specific point about something, traditional Christianity has always taken note as specifics make an event specific. Regardless of how often we worship together, it is quite clear that we are "specifically" to do so on the first day of the week; that is Sunday, specifically. Another example of the historic Church following specifics: This past friday the Church historically celebrated the the Incarnation on that date (Feast of the Annunciation); Scripture mentions it, it is specific so the Church observes it.
For traditional Christians, when something is specifically noted; it is wise to treat it as a directive. On the other hand, it seems that our Lord was always in hot water for not observing the sabbath properly.
His rising from the tomb on the first day of the week, is significant and specific, so the Church prioritizes the observation of Easter on the day that same day of the week. There is a historic prayer that mentions that the Lord has consecrated that day for our use by His rising.
So, to keep things on track and on topic, Churches that refused to observe the resurrection on the first day of the week as Scripture directs, may not be OT Christians, but they are stuck somewhere in between; not fully observing what is very clear in Scripture, should be observed.
Sorry if my opinions touch a nerve, but really, is it not good and proper to strive to observe the examples of our Lord, and the Apostles? Groups that chose not to, IMO fall outside of "the Apostolic Church" portrayed in the Scriptures.