Why are uploads sequential?

[skwp]

I see that attachinary.js forces sequentialUploads to be true. The jquery fileupload plugin's default is false (parallel uploads). Is there any reason to force sequential here?

[assembler]

Parallel uploads made it impossible to limit the maximum number of files, and to check their types. It also made it very difficult to track the progress and handle all callbacks. I decided to simplify everything by switching to sequential.