As a long-time Boltek user/StrikeStar member...
I believe that the original StrikeStar used just triangulation of the strike based on azimuth and estimated distance of the receiving stations. I don't know if the time stamp was the local computer time or the time of arrival at the server.
In any case, that relied on users accurately aiming their antennas, among other things. A few degrees error in aiming would translate to miles of error. (3 degrees at 100 miles is over 5 mile error on the far end. At 500 miles, it's a 26 mile error...)
GPS timing was not added until later and is not required. Indeed, if you look at
http://www.strikestarus.com/StrikeStarUS_Stats.html you can see that a fair percentage of StrikeStar members don't have GPS, or, like mine (huh?) are off-line. (I need to check that...)
Like other things, the Boltek receivers were designed mainly for one thing (local lightning detection) and then 3rd party developers expanded their capability.
OTOH, this version of Blitzortung seems to be designed with TOA triangulation in mind, and benefits from no need to accurately aim the antenna.