This is false. In recent history, it was closer to being true in the post-Sexual Revolution, pre-internet era (1960s-early 1990s), but it's not close to reality now.
If an average looking woman isn't getting a lot of interest in real life, she has two digital options to get more male attention without even closely examining her day-to-day life.
She can increase her activity on social media if she's not very active on social media and get more social media DMs. In most cases, her DM flow already contains enough men as she's likely already somewhat active on social media. Instagram is the best dating app out there as there are far more people present on Instagram than the Big 3 swipe apps. It's true that there are a lot of people in committed relationships on Instagram, but there are plenty of unattached people on Instagram. That's likely where she'll get most of her attention. If she uses Twitter, she probably has DM options there too. If she went to college and has some office job, she likely has a LinkedIn account. If she makes a few posts on LinkedIn, she'll get some DMs looking for dates and/or sex on LinkedIn too.
If she doesn't get enough abundance from her social media DMs, she has the option to create an account on Tinder/Bumble/Hinge. Doing this will fix her abundance problem. An average looking woman on Tinder/Bumble/Hinge has 100+ penis options. While many may want her solely for sex, she has enough abundance from having that quantity of options that there will be some men who want to commit to her within those 100+ options. For instance, this woman had 1,946 men who had already swiped right on her on Bumble without her even needing to take action. That's a lot of options.
They met on Bumble and fell into a fun, one-night-a-week, nonexclusive routine — until she realized she liked him.
www.nytimes.com
There's no average man who can come close to female abundance like that.