I don’t think it was purpose built for giving realistic estimates…it seems to be more of a SEO type of thing as calculators are often simple little tools to add to a site to gain more traction in terms of SEO.
The reason for my assumption is the estimates are nowhere near reality and as soon as it was released everybody indicated to Bubble it was off by a long way…7 months later still no change…this leads me to believe it wasn’t built in order to actually estimate true costs.