It's because there are hundreds of other people like you trying to apply with less than 2 hours to go.
Here is a summary of which SEAS application types need evidence/supporting statements/documentation.
Category 2: a copy of your passport entry visa, photograph page, and
initial arrival stamp into Australia
Category 4: statement of support
Category 5: proof of Centrelink benefits (if VTAC is not getting them
electronically on your behalf) or statement of support (if
you do not receive any current Centrelink benefits) and/or
proof of parent/guardian receipt of Family Tax Benefit-A
Category 7: SNAP form (if you selected RMIT)
Category 9: statement of support
Category 10: refugee status papers or copy of your passport entry visa,
photograph page, and initial arrival stamp into Australia