What is the point of making the port a trunk through Bridge?

Question

network hardware

You can simply add vlans directly to interfaces without using Bridge

Answer 1

There are three different ways to set up a VLAN. Creating /interface vlan and then joining via bridge is the most not recommended in any conditions. Basically, there are four possible situations:
1. Basic switch chip without VLAN support
2. Basic switch chip with VLAN support
3. CRS1xx/CRS2xx
switches 4. CRS3xx switches
Depending on the specific situation, the recommended configuration method will vary. But in any case, setting via /interface vlan is the worst option.