I think this is a mistake, and I'm not saying this as potential applicant but as an observer.
There's a lot of misinformation around and a lot of hype. Imagine you're desperate to apply, CEC is out of reach because you have a short PGWP, couldn't secure a NOC A or B job, your age, etc. This is a golden opportunity to get PR. Just check all of the "Am I eligible?" threads on the forum, on Reddit, on Youtube.
If you have all of your documents ready and know the stream might close within a hours because of all the marketing and hype, what are you going to do? Read all of the program details carefully and take your time reviewing your application? No, this is going to be like the hunger games and everyone will mass-apply as soon as they can without reading anything because this program HAS a cap and we don't know how stable the new site will be, people will panic thinking the page will crash halfway through their application.
Even in here, most of us are expecting the page to collapse (according to my poll yesterday) because of high traffic. Look at the IELTS/CELPIP sites, there's a f*cking queue just to register for an exam, look at the panel physician bookings, around TO most are fully booked until June. How does IRCC not expect the stream opening day to be a disaster? I feel they're greatly underestimating the number of interested candidates.