Then she became a mom, and everything changed.
Zaleski said she committed multiple "infractions," against these women, including scheduling late-afternoon meetings or happy hours without considering that mothers with after-work responsibilities wouldn't be able to attend.
She even didn't disagree "when another female editor said we should hurry up and fire another woman before she 'got pregnant.' "
Now a mother to a young daughter, Zaleski said she was wrong to undervalue mothers' contributions by counting hours logged in the office and not the actual work done.
"I wish I had known five years ago, as a young, childless manager, that mothers are the people you need on your team," she wrote. "There's a saying that 'if you want something done then ask a busy person to do it.' That's exactly why I like working with mothers now."
Zaleski's piece has been shared more than 1,000 times and has been hailed on social media by many commenters who applaud her for seeing the error of her ways.
"Your message is so important and it's about time it was addressed," said Heather Bouvier on Twitter.
"THANK YOU for writing this. There are so many people like your then-childless 28-year-old self who need to read it. Seriously, thank you from the bottom of my heart," wrote Alice Gomstyn on Facebook.
Since the essay was published Tuesday, Zaleski told CNN she's received more than 2,000 emails from readers who admit they've committed similar infractions in the workplace.
"I'm so motivated and thrilled," she said. "I couldn't be more psyched for the responses."
But not all the responses have been positive. Some people refuse to accept Zaleski's apology and accuse her of borrowing from similar apologetic essays by other new moms.
"This woman has basically stolen another woman's post about her views on mothers with children in the workforce for her own personal gain!!," wrote one commenter on Zaleski's essay.
Others accuse Zaleski of writing the essay just to promote the new company she co-founded, Power to Fly, an online platform that matches women with technical skills to freelance projects they can do from anywhere.
"This woman & her shameless self-promoting article disgust me. No awareness. No integrity," Kitten Holiday said on Twitter.
Zaleski said that notion is "just silly," and she's taken a huge risk leaving a stable job to start a company that is a part of the solution.
Zaleski said her company, which launched in August, enables women to work from home so that they can "be valued for their productivity and not time spent sitting in an office or at a bar bonding afterwards."
But some critics say encouraging mothers to work from home only perpetuates a problem.
"I like this article a lot, but wish the solution wasn't to have a company that helps mothers find jobs that keep them tucked away at home, but to change the dominant culture to create better, more supportive workplaces where flexible schedules are encouraged," said Suzanne Pekow Carlson on Facebook.
Others say they wish Zaleski went further, and instead of only addressing the challenges of the working mother, wished she'd included other caregivers, like dads.
"I hope the convo ... expands beyond just working moms to working dads, folks taking care of sick parents, etc.," ABC's Karen Travers said on Twitter.
"I don't understand why we still refuse to acknowledge that our society needs to be more flexible for PARENTS. It is not just the woman's burden," said Margaret Weingart Berger on Facebook.
And said another commenter on Zaleski's essay, "If it takes this woman becoming a mother to understand the value of working mothers and have compassion for them, then I guess we can't expect men to understand and have compassion because they will never be able to be mothers themselves."
Zaleski said she finds the criticism "frustrating," but said she refuses to dwell on the negative. She wants to "stay focused on helping women find fulfilling work they can do from home."
She said her essay represents her "own personal experience," which happens to mostly involve working with mothers. But she's glad her piece has opened a dialogue and she hopes the conversation continues.
Women not supporting women "is a systemic problem in our society," Zaleski said.
Serena Markstrom Nugent, posting on Facebook, agreed.
"To the women mad at her (Zaleski) and saying too little too late: She not only had not had kids but was very young and ambitious. In the spirit of not tearing down other women, I would say cheer her on for where she is on in the journey," she wrote. "Still young, still learning, and at least at this point, it appears, part of the solution."
Still other critics suggest the issue isn't as simple as parents versus non-parents in the workplace. Instead, they say, it's about the lack of empathy that exists between colleagues whose circumstances are different from their own.
"Why is it necessary to 'walk in someone's shoes' before we understand their perspective?" said Ann OConnell on Facebook. "Until we strive to have understanding and compassion for people regardless of our personal circumstances or life choices, we will remain selfish and self-centered as a whole."