I was on twitter and I saw this photo of an altar at a Maronite Church in Syria. Were there many Churches in medieval times that had altars like this?

Again you are confusing things.

1 what is pictured is obviously stone underneath a baldachino. This is not the same as a table.

2 Eastern churches do not have 'altars' n the same sense as the Roman Church. Yes the sacrament is said on an Altar, but the altar is the tablitho/antimension. This is why until WWII in general it was forbidden for a Latin cleric to say mass outside a church without a portable Altar stone. The Pope gave permission to use eastern antimension to chaplains. This permission now results in intentional misuse of these objects (every antimension/tablitho is made with writing saying essentially Bishop X gives Fr X permission to say mass. This is to be returned to the bishop after the priests death because it is no longer a valid altar. The antimension is a canonical permission for a particular priest.)
Mass is to be said on an Altar stone, this is supposed to be a permanent fixture in an Altar or at the very least in a temporary structure in a church. That's the consistent Roman tradition. The Pope's have made it quite clear that we are not to adapt this custom we say mass over the bodies or recognizable relics of saints in a church. Anything else is foreign to the mass in the catacombs where our glorious tradition arose from