One of the advantages of aligning the budget and the main estimates, from a government perspective, is that you can implement things earlier in the fiscal year.
One of the things they talked about in their discussion document is that some things take from 15 to 19 months before Parliament approves them after announcement in the budget. If you are able to present things and implement them earlier in the fiscal year, it's easier. If you have to wait until December to get parliamentary approval to spend money, you have three months left to spend the money.
With respect to provinces, most of the transfers are under statutory authority and don't go through the estimates, so that particular thing might be less affected, but non-governmental organizations and first nations communities get money well into the fiscal year. They're told they have to spend it within a couple of months' notice. It's not really a good way to design a system.