To add to what already has been said, when writing music, its really a matter of using the tool you are most comfortable in. When it comes to abilities between a tracker and a sequencer, nowadays they are mostly equal. By that I mean, if one knows the tools well enough, they can make the exact same song in both pieces of software, but it may go easier in one vs the other.
It is this nuance that makes it so that a tracker is not that widely used. I do use OpenMPT, but I also use a sequencer but for different type of projects. When creating a song, my methodology is different for a tracker vs a sequencer. In a sequencer, I'll record my midi notes using a keyboard while I hit the record button and do it track by track. In a tracker, I work pattern to pattern and usually work in groups of 4 patterns.
The biggest reason for me to go for a tracker over a sequencer, is if I want to create a module, for example for a demo project. Another reason could be to create chiptunes, something that is so much easier in a tracker.
So... it really does matter what one would want to accomplish whether or not their choice of software is determined on beforehand.
When it comes to modern music, one should keep in mind that a tracker works really well when you are one person composing the entire music. If you are in a band/group and you want to compose as a group, a tracker will make things so much harder than a sequencer by definition alone because you then have performers. They just want to play their instrument, so all you need to do is hit record. One could even just hit record and have a jam session, and then one person uses whatever was played to construct the real song, something that is much harder to do with a tracker and external sound recorder.
