DURING Facebook, Inc.’s global outage on Monday, online clothing boutique Exul recorded no sales for the first time since it opened last November.

“Every day counts, every penny counts for a small business,” said owner Porsche Jones.

Ms. Jones doesn’t have a large marketing budget, so she relies on Facebook and Instagram to target and communicate with potential customers. “As long as I’m active on social media, I’m producing some kind of value,” she explained. But when a technical issue kept Facebook’s social media properties, including Instagram and WhatsApp, offline for almost six hours, Ms. Jones couldn’t post pictures of new merchandise or news of a sale.

The disruption affected more than just Jones’s marketing. She also uses WhatsApp to communicate with her packaging suppliers, so she couldn’t place orders.

Now, with the whole network of services back up and running, Ms. Jones has to make up for lost time and she never wants to end up in a similar situation.

The worldwide crash laid bare just how much of the world relies on Facebook’s services, leading to renewed criticism that the nearly $1-trillion company has too much power. Regulatory authorities in the US and Europe seized the opportunity to focus on Facebook’s dominance and the “serious consequences” of dependency on one company for key communication channels, according to one German member of the European Parliament. But on the ground, the effects weren’t just esoteric.

The outage was a lesson on diversifying to other platforms, Ms. Jones said. She spent much of Monday on Twitter, learning how to use the app and working to grow her engagement. She is also now planning on advertising on Pinterest, Inc., connecting with clients over e-mail, and even creating in-person pop-up stores in her home city of Houston.

In Northern Alberta, Canada, small-business owner Carolyn Gerk was struggling with a similar marketing issue. Ms. Gerk runs Velvet Hand Designs, where she sells ink and watercolor portraits, logos and prints online and has an Instagram storefront. “I live in a rural location, so in-person sales, markets, events can be very limiting. I need to be able to connect with people,” she said. Instagram is her main marketing tool.

Facebook and Instagram facilitate Ms. Gerk’s ability to communicate with other small business owners. Given her remote location, Ms. Gerk said the ability to share advice and support online is essential. In the time that Facebook’s apps were down, she said she felt a noticeable absence. “It was striking how quickly we had to become detached from one another for that short time.”

And, in the tangled, convoluted way that the modern world works, Ms. Gerk’s inability to sell her goods in Canada was also impacting women in Texas.

Ms. Gerk is part of a small nonprofit group called @truecrimecreatives who donate 15% of a week’s worth of sales to a charity once a month. This week, the group is raising money for an abortion rights organization in Texas called West Fund. “It’s discouraging to lose any of the advertising for that week,” she says.

Now, like Ms. Jones, Ms. Gerk is thinking about ways to expand to other services. She’s focused on increasing engagement on Twitter, Inc. and ByteDance Ltd.’s TikTok.

Facebook shares gained 2.1% on Tuesday in New York. — Bloomberg