And how many closed loop ecologies functioned for any significant length of time without constant resouces and parts from outside being put in? Not to mention without lead times of 9+ months on those supplies, and not having to worry about large pressure differences and leaks, radiation, or extremely abrasive enviroments?
Of course the science has to be done and is useful, but there is still a huge leap between doing it on earth and doing it in an entirely different body and harsher enviroment, and we haven't done it on earth despite many attempts.
Its not like its just some small details that need some fine tuning or funding to achieve and just around the corner. The scale of building just an empty multi-acre structure off earth to start would by itself dwarf all our previous space projects combined.
