Nope. It’s also not true that it was because Betamax was too late as many claim. Betamax came out in 1975 and VHS in 1976.
So Betamax actually had a slight head start.

The reason Betamax lost was that Sony had exclusive rights to Betamax, and they tried to monopolize the market.
VHS was a way more open standard all could use, which lead to the obvious result that everybody that made video-recorders made VHS.
With the way better availability and more competition on VHS recorders, and VHS being cheaper to make to begin with, prices on VHS were way more more competitive. This was a significant factor because video recorders were very expensive early on.
The tapes were also cheaper for VHS, which probably was a factor too.

This of course led to VHS also being by far the preferred format for video shops, as there was a bigger market for VHS videos.
Some claim that the way wider availability of VHS movies in video shops was a factor too, but this was IMO more a result of more people already owning VHS videos when video shops became popular. And if you loaned/rented a moviebox with your videos, those were also always VHS, for the obvious reason that they were way cheaper for the shop.

So in short, it was all about price and availability, because that shit was expensive early on, and I bet the porn industry chose VHS for the exact same reason everybody else did. It was cheaper for them, and being cheaper for consumers too, you could reach a wider audience, meaning you could make more money.

I’m also not really old enough, but I thought it was license costs (as usual with Sony).

It may have contributed to the failure of Betamax, but there several reasons for the failure of that format.

1. It was expensive. From the cameras to the playback machines, even commercial distribution on Betamax tapes came with an expensive license and fee that VHS did not have.

2. Betamax tapes (initially) were limited to 60 minutes. The VHS tapes were initially 120 or 180 minutes.

3. Betamax machines and Betamax camcorders were much more bulky and heavier and more complicated to use than their VHS alternatives.

Despite its superior quality, Betamax came with a lot of drawbacks, all of which were the major contributors to its downfall. How much porn itself had to do with that, it’s probably not known, but it was not a major contributing factor.

Was around during the time an I can say with absolute certainty all things Sony including the Betamax products were smaller with a better overall user design (think buttons and external displays). Sony was just better than most every company when it came to analog video and portable audio.

Regarding licensing fees, consumers rarely saw those fees because they were mostly renting movies. Few people ever mastered the art of recording television shows in the US (fewer purchased recorders). And when they did it was oftentimes while they were at home. Literally everyone of that generation had a VHS whose clocked flashed because the owner could not set the time. I mention this because setting the time was required if you wanted to plan a recording while you were away from home.

I mention all of this because these machines were used by a generation who never utilized them for anything other than renting videos and recording while at home.

Beta lost because of marketing and the lack of choice among Betamax devices (this is where the licensing came to play).

If the person making the audio/video choices was technical or an audiophile they purchased a Betamax.

Not to be overly critical but that generation relied heavily on marketing to make those types of purchasing decisions. Product quality or the feature set could be easily overshadowed by dynamic marketing.

Regarding porn, there was porn on video but during the VHS/Betamax period most porn was in magazine form.

you are not the first one asking the question

https://duckduckgo.com/?t=ffab&q=vhs+vs+beta+vs+porn

https://en.wikipedia.org/wiki/Videotape_format_war#Contributing_factors