Yes, It was a pretty known alternative back then. 95-97 when I was most active.
Why buy Tamiya X-20A to thin acrylic when you can buy a gallon of distilled water for $1? Same analogy. :)
Because you get way better performance when using the Manufacturer's own thinner. Tamiya X 20A contains a retarder and helps the paint level out. Water is a poor thinner for any acrylic paint.