A platform profile can get the job done, especially when you are just starting out. But there are things a personal website gives you that a profile page simply cannot. You control the story you tell, you are not competing for attention on someone else's platform, and you are not at risk if the platform changes its rules or shuts down your account. Clients who find you through a website also tend to take you more seriously. What do you think a freelancer actually loses by not having their own site?