Well, I can only speak from my own experience.

When the PS5 launched I wanted to upgrade but you literally couldn't get it because it wasn't in stock anywhere. You could only find it on eBay of some private seller that started at almost double the price, no, thank you. Then Sony introduced this "Register and on the next event you get a slot to buy one from the official Website" which was great. I got invited the first time and literally couldn't buy it because the website was broken. Whenever I wanted to select my payment method the checkout got blank and there was nothing you could do. Even worse was that you couldn't hard refresh the shop because this would have killed the session that the website needed to allow you to buy it. So, even switching browsers with the same "invitation link" didn't work. I reported this to the support, but they didn't really care. half a year later, I got my second invitation link and the same happened then as well. I reported it again to the support, but they still didn't know what to do with that information or wanted to troubleshoot this.

And now, there isn't really a need for it anyway. The Games that I would have wanted to buy on the PS5 released on the PC.