Marc Jacobs subtly used a plus-size model in a runway show

It's rare to see a high fashion designer place larger models on the runway.

But Marc Jacobs just set a new standard.

At New York Fashion Week, the designer featured plus size indie rock singer Beth Ditto, Rachel Lubitz of Mic points out. Perhaps more significantly, Lubitz notes that there was no big hoopla made about the plus-size model's appearance. 

Lubitz points out that Ditto wasn't an opening act nor was she the grand finale. In fact, she strutted amongst some of the most successful models in the business - namely, Kendall Jenner, Bella Hadid, and Emily Ratajkowski.

Ditto is no stranger to the runway; she strutted the stage for Jean Paul Gaultier five years ago - and she opened and closed the show. She told The Guardian she found the experience to be "amazing and frightening."

So she's a pro at this.

Perhaps even more crucially, Ditto's dress was not hideous. The retail industry is known for limiting plus-size designs to matronly frocks.

In 2013, online retailer ModCloth conducted a survey with Paradigm Sample to find out how plus-size women felt about the market's offerings. They felt they had slim pickings and shared a mostly frustrated sentiment. Additionally, only 28% of the women polled agreed with the statement "plus size women are included in the fashion industry."

The fashion industry is notoriously exclusive, and the retail industry tends to echo that ethos. Victoria's Secret not only refuses to let plus-size models walk its runway, the retailer does not sell larger sizes.

Many retailers ignore larger women, which baffles many women because the plus-size category is worth $17.5 billion, according to industry research firm NPD Group. 

But the avoidance is not without cause.

The reason many designers stay away from crafting clothing for larger women is twofold: they're afraid and they simply don't know how to.

"I would argue that why many non-plus-size designers don't go into plus-size is fear," Amanda Czerniawski, sociology professor at Temple University, former plus-size model, and author of "Fashioning Fat: Inside Plus-Size Modeling," told Business Insider.

Because many companies aren't familiar with designing for plus-size clientele, they might be intimidated by making the investment.

"Many of these designers, when they go to design school, they're not taught to make clothes for plus-size bodies," she said.

Meanwhile, plus-size models are challenging the industry. Plus-size model Ashley Graham appeared in an ad in Sports Illustrated earlier this year for swimsuitsforall, and she even has created her own sexy lingerie line for Addition Elle.

Plus size models do occasionally make appearances on the runway. Paris Fashion Week 2010 - the same season in which Ditto walked for Jean-Paul Gaultier -  was singled out by New York Magazine's The Cut for "doing much more for the plus-size model movement than New York Fashion Week."

At the time, Gaultier expressed that he cared not for such restrictions. "What counts is personality, there is not just the one form of stereotyped beauty. This collection's pleats can be worn by any size and adapt to different body shapes," he said, according to The Cut.

High fashion still remains a tricky territory for lager women, but Jacobs and Ditto just helped plus-size women - and the fashion industry - take one huge step.