At PRYME Homes we do this 98% of the time.
There are a couple reasons why we like this so much:
Save money of the GC fee. We completely cut out the GC which means we get the job done at cost. This alone can save you tens of thousands of dollars when flipping houses.
Control of the project. We can control who does what and when. This is crucial to making sure everything stays on track. We can schedule all of the contractors so everything flows.
Replace contractors. If you hire a GC, it's harder to replace them because they tend to jump around on the SOW. But with a tradesmen, you can replace them just for their SOW.
When flipping houses speed is everything. For many investors, you have money you've borrowed and are paying interest on. If you hired a GC that has a small crew this can delay your project a lot. In a small crew everyone does everything. This makes it really hard to do more than one scope at a time.
The downside. Hiring individual tradesmen requires more work.
You have to find them. This means calling around, asking for referrals, going to other peoples projects.
Even after you found some "good" tradesmen, you have to keep looking because they may not last. Ever since we have been renovating houses we have needed new tradesmen after each project. Sometimes they only last one project. Other times, we need a different skill level.
There's no "one size fits all" tradesmen. If you have a great worker for high-end tile jobs they may be too expensive for lower-end. We don't use the same workers for a $500K house as we do for $150K house.
Once you find them, now you have to manage them!