When I worked for Mattel in the mid-1980s, I spent a fair amount of time with the trademark department, which wanted to make sure that, when I was using a possessive in a company publication, it read Barbie doll’s instead of Barbie’s. Barbie is a trademark and can’t be altered, even for correct punctuation.

These were busy folks. No violation of a Mattel trademark went unchallenged. There was that famous action taken against MCA Records over Aqua’s song, “Barbie Girl.” The company’s philosophy, our trademark lawyer told me, was that letting the smallest of transgressions go opened the door other trademark violations to pass legal muster because of the company’s previous lapses in defending its IP.

At the time I worked there, Mattel was the number one toymaker in the world. Today, that honor belongs to Lego, a company that notoriously lets a lot of people do with their products whatever they like. Lego notoriously welcomes hacking of its products. According to a 2005 C|Net report, “The Lego honchos (see product hacking as) an opportunity to lean on the collective thinking of an Internet community to improve their own product while bolstering relations with committed customers.” It’s an attitude that has served the Danish company well.

The Web is loaded with independent Lego fan sites. BrickInstructions.com is one of them, a site that is supported with advertising from brands ranging from LG to TripIt.

What does Lego know that IKEA doesn’t?

Fans of a site called IKEA Hackers have gathered the torches and pitchforks to assail the Swedish DIY furniture company’s cease-and-desist letter aimed at site owner Jules Yap. The site provides insights into ways people can modify and repurpose IKEA products. The letter originally required Yap to give up her domain name but has backed off, insisting only that she remove the advertising that supports the site.

IKEA responded to a Marketing Magazine request for comment by digging in its heels. “We have a great responsibility to customers,” the statement says, “who should always be able to trust the Ikea brand…When other companies use the Ikea name for economic gain, it creates confusion and rights are lost.”

‘Scuse me?

I’m no lawyer, but I see no opportunity for confusion with the ads of Yap’s site. The names of the companies—which offer resources for enhancing IKEA products, such as handmade doors for IKEA cabinets from a company called semihandmade—actually encourage people to buy IKEA furniture.

But whether the ads benefit IKEA or not, the key mistake here—one LEGO would never make—is discouraging a brand ambassador who is undoubtedly generating sales for the company. Yap is part of an ecosystem IKEA should be encouraging rather than threatening.

“Needless to say, I am crushed,” Yap blogged. “I don’t have an issue with them protecting their trademark but I think they could have handled it better. I am a person, not a corporation. A blogger who obviously is on their side. Could they not have talked to me like normal people do without issuing a C&D?”

Indeed. The situation is a lot like the Ford Ranger Station saga, in which former Ford Motor Company social media honcho Scott Monty posted well over a hundred tweets in about a 12-hour period, helping to defuse a controversy when the automaker’s lawyers send a similar takedown notice to a brand ambassador running a community site for fans of the Ford Ranger pickup truck.

The company initially demanded the URL be turned over to the company along with $5,000. When Scott injected himself into the situation, he was able to facilitate a conversation that resulted in the site staying up under the same URL and without a financial penalty. The site owner did agree to stop selling decals that were counterfeit. But the site still has advertising that doesn’t seem to trouble Ford’s lawyers—not even an ad for a Toyota dealership!

IKEA’s lawyers are undoubtedly be right legally speaking, but the company is dead wrong. IKEA should have embraced Yap long ago based on the influence she wields among her readers and recognition of the importance of independent third-party voices in building support for the brand. Alienating her can have consequences that far outweigh any perceived damage her site’s ads (which undoubtedly provide her the income she needs to devote time to the site) cause the company.

George Santayana famously said that those who don’t remember the past are condemned to repeat it. In IKEA’s case, you have to know the past in the first place. They should bone up on the LEGO and Ranger Station stories before making this mistake again.