I typed "12 c in f", a very simple example of the sort of thing I use wolfram alpha (usually by way of duck duck go) for most often. It choked. I bailed.

I'm a Linux user. I have bc and units installed. I even have some shell script wrappers to make those utilities actually helpful for casual use. I can open a terminal and calculate expressions and convert units...so long as I ask nicely. The big win for W|A is that it doesn't require me to ask nicely. This is helpful for quick 'n' dirty queries as well as for queries where the work required isn't in doing the calculation so much as reducing the query into a simple expression in the first place.

In other words, simpygamma solves a problem that by and large doesn't exist.