Speaking at a session on the future of online ad sales at the Association of Online Publishers' Digital Summit, Maples said he did not believe all traditional ad sales will be replaced by an automated process.
The "nirvana" of traditional sales being achieved automatically so sales people can be left to have interesting conversations is a myth, said Maples.
Maples said it was "absolutely important we have direct relationship with agencies. That can't be done automated or through a third party [such as an ad network]. That's done through relationships. That's done through responding to briefs. Automated systems don't replace being able to do a good job yourselves."
The panel session also included: Katie Eyton, executive director, head of digital at Manning Gottlieb OMD; Sacha Bunatyan, general manager at Aegis Media's trading desk Amnet UK; and Fabien Magalon, managing director of the ad exchange La Place Media.
When he started in TV in 1990, Maples said the industry was talking about automated sales and years later, he stressed, "We're not really much further down the line."
He added: "We're able to have a bit more of a stab. The ability to continually build relationships will always be a fundamental part of the business."