The straightforward answer to this is that full-time workers are incentivized to stay more committed to work. Since these employees work on core tasks and are also rewarded with different compensation packages, they feel like a part of the company. This makes it convenient for them to be relatively loyal and take up more tasks. Additionally, investing in full-time employees might also be a worthy investment for a company looking at long-term goals.
The downside, of course, is that it takes a lot to onboard full-time employees. If they don’t spend a long time with your company, you might have to spend a similar sum to onboard another employee.