Portals like MyHammer, eBay, Ferienwohnung-direkt, Immonet, Hrs, mobile, Amazon, etc. are also just offer sites or intermediaries where others register their account or goods/services for sale/offer. It is worth it as a user (whether with or without IT knowledge) to read the terms and conditions. Of course, no one/everyone [emoji6] does that, yet buys cheaply and naively (whether services or other goods), and then blames the portal.
You don’t even need any IT experience or a high school diploma to know how the portals work.
That it was abolished at some point to give negative reviews is new to me, at least with MyHammer… (because I haven’t been there for ages)… still not really new either, I remember updates on eBay years ago when the rules were revised there because targeted bad and false reviews can ruin a good company. You could compare it somewhat to bullying. Currently repeatedly a topic in many TV reports, most recently a ruling against Jameda to delete subjectively bad reviews without neutrality.
It is not without reason that there is a moderated subforum for company reviews here in the forum, and an affidavit is required for bad reviews.
As a responsible citizen, you should also know how to deal with employees or telephone operators in a company’s call center: politely. They are not the scapegoat for angry users or customers. You also don’t need a school degree for that, only some foresight and polite manners. What goes in comes out. Then the call is simply hung up so the angry person has time to get some fresh air and reflect for half an hour [emoji6]
Edit: just as you can register as a business on MyHammer, you can also register on Ikea. So it could also have happened to you through Ikea’s database, by finding your “bad” craftsman via regional search