I est about 99.9989483% internet sites have Interstitial content. Unless the site is self-hosted, completely private, with their own registered URL, and it never touches a BOT detector(Cloudflare, et-al) or way station it will have Interstitial material. Beechtalk is not self-hosted, neither is POA. Both have ads, and links to various other sites, and they all have click-direct counters to accurately determine the value of the links to paid sites.
It's extremely rare for an Interstitial host/server to jam up the site(like Beechtalk), but it could happen. As for the 'Cloudflare' problem, well - it's the same ole same ole. How to detect and shunt/block bots from hosted sites, while still serving up desired content to humans with the minimal delay? The open nature of the WWW and all of the non-WWW internet makes it possible for bad-actors to operate. The lack of regulation and oversight by any governing body world wide is the bloom of market value, and just as well the stench of bad actors using the platform for nefarious purpose.
Alternative sites for checking what's down on the web is downdetector.com. A bit more granular, but suitable for most sites, and valuable for larg hosting sites like L3, ATT, VZW, etc.