Mobile apps and some mobile browsers don't support ad block.
While I have ublock on my laptop, i still get ads when I am on my phone which ironically is where these companies get most of their revenue these days.
If you have a Raspberry Pi, look into using Pi-hole[1]. It provides network-wide blocking when installed on your home network by proxying requests. I also use AdGuard Pro[2], which provides a similar function when I'm outside my home network. Both happen to be open source software[3][4], so that's a plus.
> Not for iOS though, atleast without a jailbreak.
If you have persistence, no jailbreak is needed. Would require you to binary patch the executable then resign the binary using your own Apple Dev account. Far from trivial, but still doable and without Jailbreaking.
if you have android you can get Netguard from github [0]. Its from the Xprivacy dev; functions as a firewall (VPN), w/o root. The github version supports ability to load Hosts file that can block domains (ads) - like the hosts files used by Ublock. This generally blocks ads across the OS. iOs should have something similar.
The goal of NetGuard is to function as a Firewall to limit apps ability to phone home without consent. The host file feature will block most in-app advertising and provide some protection for web browsing. Ads within facebook can be blocked using custom host filed within Ublock/Umatrix. I dont know about ad-blocking within the FB app itself.
Generally, you should be using Firefox, not Chrome, with Ublock and/or Umatrix installed to maintain control of your web experience. FB web interface can be used and ads generally blocked. Reddit's native ads are served directly via first party URLs so it is tuff to block. Reddit's made changes for the advertisers and their new UI is meant to popularize Native ads.
The necessary knowledge about the existence of content blockers as well as the technological literacy to set them up is probably a given.
He also probably has a high value attached to his attention, given that he is in quite a power position. This, I'd argue, would make a greater reflection of media habits more likely.
Additionally there might be the security/privacy aspect. Executives should really focus on security as their devices might be of greater value than your average grandmother's Scrabble tablet.
However I think that it is not very speculative to say that, if more people knew about content blocking, more people would block unwanted content. My intention behind assuming his knowledge/competence was only meant to exclude nescience from the list of potential reasons for him to not block content.
Personally I'm thinking that since he's the CEO of a company which monetizes on ads it could be that he wants to follow ad trends, see what's going on in the ad space, what other people are advertising etc.