If ad blockers were a big problem YouTube would deal with it, tons of sites already deny you content if you have one.
Thing about ad-blockers, they merely allow your computer (including mobile devices) to decide which items to download. Although the laws in various countries have contrived to make this simple autonomous decision seem murky, it's really just computers doing what they're supposed to do. You own the computer (or phone, if that's what you want to call it) and you get to tell it which data you wish to accept. The website or app may present you with a list of content for you to stream or download, but this doesn't oblige you to do so.
There are techniques to stop presenting content if there is an ad-blocker, but there is no effective way for a website to do this. Your computer (or phone, or whatever) could easily spoof the website.
On the legal point, it might be that the law in some country says you must download all advertising content. But okay, then what? If I choose to watch an episode of a podcast but then mute the sound or cover the screen with a cardboard mask, what business does the law have to dictate that I behave otherwise?
So the law may say I (a horse, yes did I not say I'm a horse?) must be taken to water, it seems to be extravagant to require that I drink every drop. I could be required to download the crap, but I don't see how the law can be used to compel me to consume the parts I don't care for. And I can automate that decision, because it's a computer and I decide how it presents data.
So ad-blocking of some sort or other seems to be, well, unblockable.
