These "ceremonial" sabbaths were very connected to the agricultural cycle of the land. These were times of the year that was related to things they needed to do for their crops and local economy. Ancients felt that they not only needed to do the planting/harvesting etc. but that they needed ritual to go along with the actions as well as these ceremonies are reminders of what they need to do. These were times that the people living in the land had to focus on what was needed for the agriculture and local economy. This was especially needed for this piece of property due to the competition of the biology and weather of this "land of milk and honey" of the meeting between Europe, Asia, Africa and Arabia. (Our popular western picture of the term "milk" and "honey" were NOT what they were dealing with.)
These "sabbaths" were kept by the Canaanites centuries before Abraham was even born. Now, the Canaanites ended up corrupting the understanding of these key points in the annual cycle. In trying to deal with the complicated issue of a land flowing with both milk and honey, the Canaanites developed some horrible rituals and superstitions. Since the Hebrews needed to live in this same schedule, God gave them the feasts of the land or "ceremonial" sabbaths. God was very strict as to what ritual was acceptable for the Hebrews to continue to use. God took these "acceptable" parts and changed them into not only helping with they cycle of the land and economic cycle, but to also learn truth about who HE is. God also strictly forbade other parts of how the Canaanites worshiped on these cycles.
When in exile, those who were left in the land needed to observe when it was time for the feast and a chain of smoke signals were set up to notify the people in exile to at least pray for the land and the cycle. Those living in exile or otherwise outside of the land would depend on this chain of smoke signals. Sometimes people who lived along the line of places with smoke signals, knowing that the feast was approaching would send up their own smoke signal to set off the chain and thus get the Hebrews to start keeping the feast a day or so early. (This is why rabbis eventually set up ways of figuring out when the feasts should be.)
While they needed the smoke signals or figuring out when to keep the feasts of the land. They did not need smoke signals for THE Sabbath. It was whenever the sun set on the 6th day wherever they were. The "ceremonial" sabbaths were the feasts of the land. THE Seventh-Day Sabbath was universal and would come to you wherever you were on earth. Those in Babylon greeted the Sabbath when the sun set in Babylon. Then when the Sun set in the land those left in the land would greet the Sabbath, and a little later, as the sun set in Egypt, they greeted the Sabbath when the sun set there. As Jews went farther west or farther east, they would greet the Sabbath when the sun set wherever they were.
The feasts of the land did not have this same universality that the Seventh-Day Sabbath held. As the gospel was spread to people who were not connected either directly or emotionally to the agricultural cycle of the land, it would not make sense for them to keep these ceremonial sabbaths. We can learn the lessons about God that the feasts teach, but without being somehow connected to this local agricultural cycle, the sabbaths would not apply to our lives.