Yes, this is true. It's just that there is one exemption that is not useful for most people but could work for a couple - if you are a shareholder of a non-Slovak entity that has retained profits from the tax years between 2004 and 2016, and you receive the dividends now as a Slovak tax resident, there is no applicable taxation.
So, if you own any foreign entity that still︀ has profits from that time period, it is possible to avoid paying dividend taxes on︁ them in this way.
Nevertheless, you are right, operating whatever foreign company from Slovakia will︂ make it tax resident in Slovakia.
Theoretically, the current status, of 10% on dividends from︃ foreign entities, can still be useful for tax strategies, because Slovakia is a nice place︄ to live (if you can tolerate being in the EUSSR) and if you can demonstrate︅ foreign substance, it's probably OK. Although being governed by SMER and SNS is not ideal.︆