nope. I think you might be mistaken 4k online streaming on smart TVs like smart 4K TVs. i think big studio movies release 4k online streaming on some websites like Vudo or maybe Hulu for consumer purchase maybe like as early as a year or 2 ago.
4K TVs probably first debut in late 2012, but they are ridiculously expensive because its still very new that time. So, its been more than 3 years and 4K TVs has come down a lot in prices which is cool. So maybe you mistaken that when 4K TVs first come out a few years ago, you probably thought 4k blu ray players also come out during that time or so.
But so far there haven't been a disc based video player that supports 4K yet. This year is the first year they finally release 4K UHD blu Ray players. Early last year panasonic planned on releasing 4k UHD players somewhere in the middle to late last year but they changed their plan. Maybe they are trying to get the specifications for 4K Blu Ray finalized and fine-tune and tweak it some more to make it better or something. So it was pushed to this year. I think Samsung will be the first company to release 4k UHD blu ray players in March 30 of this year. if not the first, one of the firsts.
Speaking of 4K blu ray players, what excited me even more than 4k resolution is HDR (high dynamic range). and Samsung will be the first or one of the firsts UHD Blu-Ray players to support HDR. two popular HDR formats are Dolby Vision and HDR10.