Go look up "Occam's Razor" and then come back to us.
They did not "come up with a theory" as you suggest.
Nice wording by the way, really subtle (not) attempt to portray a police investigation as "coming up with a theory" to facilitate you to then attempting to draw equivalencies with your own crackpot theories.
There is a vast difference between what the police are doing - Working the scene, taking into consideration all the likely possibilities to formulate the most probable outcome(s).
And what you're doing - Which is reading Social Media and newspaper clippings and then attempting to completely dismiss the most likely, obvious and reasonable explanation for her disappearance, in order to cling to some conspiracy-theory-esque claims that require 10 different hoops to be jumped through to make happen, with absolutely zero supporting evidence there was any foul play.
Why is it you choose to completely and repeatedly ignore the most obvious and likely, in favour of repeatedly parroting your own unfounded, unsupported, unevidenced claims that it's either "Something Dodgy" or "The Police being Incompetent"?
A psychologist explains why people believe in conspiracy theories
Tinfoil hats at the ready, conspiracy theories have become plentiful during the pandemic with many factors helping this process.
www.sciencefocus.com