I think for someone that has gone through a startup program most that is written in the article are obvious truths. Yes, there might be a lucky few who benefit from a demo day, because that's one of the few chances where you might get the attention of investors that might usually not be that easy to reach. However most people will meet their investors during the program via some connections.
To me, demo days feel like they are mostly PR events for the accelerator. It is a very easy way for an accelerator to get people to notice it, since it is one of the few events an accelerator is usually hosting, where they have significant presence and they can attract a lot of reports with the startups. Apart from that, it is very hard, especially for smaller accelerators, to even be mentioned in an article of one of the startups they funded.
To me, demo days feel like they are mostly PR events for the accelerator. It is a very easy way for an accelerator to get people to notice it, since it is one of the few events an accelerator is usually hosting, where they have significant presence and they can attract a lot of reports with the startups. Apart from that, it is very hard, especially for smaller accelerators, to even be mentioned in an article of one of the startups they funded.