VLAN 1 is used by default by Mikrotik, this it NOT normally evident because - being a default - is not normally shown in exports (you need to make an export "verbose" to see it and how it is used on interfaces and bridges), fiddling with it (unless you really-really know where your towel is) is a perfect recipe to create "strange" behaviours (that can be extremely difficult to troubleshoot) hence the first two Rules of the Mikrotik Club:
The twelve Rules of Mikrotik Club
Read with particular attention the corollary to Rule #2, it is not that much a limitation to be free to play with only 4093 VLANs instead of 4094.
Remember how behind all myths and legends, including the one about the bogeyman there is at least a grain of truth.
It's better not to make fun of the bogeyman ...