No, I don't think it's that simple NeonGolden. Plus there is no published evidence that 99% of men currently use porn. In all the surveys that have been completed, the percentages of males who have used/been exposed to porn at some time in their lives is undoubtedly high (because society expects it of them) but lots of intelligent, evolved men reject it later, especially those who realise its provenance.
The research also makes the distinction between secret porn use and that which is used with the full knowledge and acceptance of a partner. But here it gets a bit murky - lots of people within this category seem to know their partner uses porn, but very rarely do they know the extremity of the porn accessed - or how frequent the use. Still more either don't know, or don't want to know.
It's more complex than a lack of communication and sharing of fantasies. What often happens is that an addiction takes hold, the porn accessed needs to become more extreme to provide the "hit" and often the user becomes totally de-sensitised to sex within a relationship where there is mutual respect and dignity. Instead, the user gets used to seeing women demeaned and objectified. Very often, the associated masturbation is preferred to RL sex with a partner, or when sex happens it becomes more brutal/pornified - and commensurately less appealing to a partner, who is then accused of "not wanting sex". Some women believe this about themselves too....
Cumulatively, what happens then is that secrets, lies, manipulation and misogyny pervade the relationship and where I think you are right is - there is no sexual or emotional honesty.
When the opportunity to practise some of these porn fantasies arises with a real-life partner, it really isn't so much of a barrier to cross. The "fix" just becomes more extreme and the secrets, bigger. Tellingly, the porn use doesn't stop either - countering another myth that men use porn when their sexual needs are not being met or their fantasies are not realised.
I remember reading a interesting finding though - the third party is rarely someone with whom the man wants a full-time, long-term relationship; more a case of "she'll do"....so again, a pretty deep- rooted disrespect for women.
Lots of couples find that it's impossible to rebuild a relationship after infidelity while porn is still a spectre.