"Ad blocking is a hugely hot topic… There has always been ad blocking. Ad blocking was the 30-second TV ad coming on air and you got up to make a cup of tea. That was real physical ad avoidance and what did we try and do to stop that happening is to create more engaging advertising.
"There is a huge fragmentation and clutter out there in advertising absolutely, and so people have more choice and I totally agree [that] this idea of the attention economy, of course people have choice, they can switch around more, and hence if we as advertisers don't show great advertising, people switch around more," he told CNBC during the Advertising Week Europe conference in London in March.
People are continuing to download ad blocking software: there were 615 million devices blocking ads globally in December 2016, an increase of 142 million on the previous year, according to a February 2017 PageFair report.
"We have a ton of Millennials and they are not going on TV, so it's about how do you find them in ways that's not so interruptive and annoying?" Meredith Jurek, Self Esteem Brands
For Sanjay Nazerali, global chief strategy officer at media agency Carat, ad blocking is a welcome wake-up call. "I have to say I am really excited by ad blocking, which is incredibly controversial in our industry… If it is forcing brands to speak with greater meaning, with greater relevance and greater value ultimately to consumers, bring it on," he told CNBC by phone.
"We have languished for much too long, and the ability to throw messages out there that we assume that people are just going to watch, without any sense of the value that we are offering people. And guess what, they are saying they don't want it anymore," he added.
Ad blocking means marketers are looking to be more creative about how they reach consumers, and one way they're doing this is by using "influencers," or people who have a lot of followers on social media, to communicate. Nearly half (48 percent) of advertisers said they planned to increase their spending on influencers, according to a poll by agency Linqia of 170 U.S. marketers in December 2016.
However, ad spend on Instagram is increasing. It said in March that it had 1 million advertisers, an increase of 400 percent year over year, while 100 million members joined in the six months to December 2016.
But not everyone is convinced that an ad-funded model is the way to go on social media. Billionaire businessman Ayman Hariri founded social network Vero with the aim of reaching a more grown-up audience, but without advertising.