Is it right to publicly blast a company online because of one bad employee?

Inspired by another post here.

I've been seeing now more than ever that when someone has a very bad experience at a place of business (and I'm talking very bad like discrimination, telling a mom she can't breastfeed there, overreacting worker) that the first inclination nowadays seems to be to publicly blast the place of business online be it spreading on Facebook, call for a boycott by a viral tweet, etc.

No doubt these have made results (we all remember the Starbucks racist discrimination controversy) but these controversies tend to start with one bad worker as opposed to an entire business. Just in talking to one of my friends who was working for Starbucks at the time, the entire location had to go in for a multi-hour training meeting on their day off about not discriminating against customers even though there had never been a problem of discrimination at that location before. But this all ultimately started with one racist worker, a viral video and a call for a boycott.

IMO, it doesn't seem right that innocent workers have to deal with the after effects of online public shaming, be it a decrease in hours for a time because people are boycotting the company or retraining for a problem that the vast majority of workers didn't have. Especially since the offending worker is usually fired soon after and no longer has to deal with the situation. To me, I've always felt that it's better to go to someone higher up (manager, regional manager, company owner) and give them a chance to rectify the situation first before labeling the whole company as discriminatory.

So my question is, should an entire company be forced to deal with the repercussions caused by one bad worker because of it being made public by social media? And by extension, has social media made public shaming the preferred method of taking action instead of trying to handle issues privately first?