I'm fully prepared to walk (better to have $1,000 learning experience than a money pit), but the last thing I want to is to be running around on Friday the day of my initial deadline trying to get an extension signed or trying to cancel the contract before I'm locked in.Sorry for the mouthful, but I would appreciate any thoughts/perspective. 

Only the poor PMs feel the need to lock you in.  

Locked in my rate today figuring if a vaccine comes out the rates/market will go up, I think my decision is made, always tough to decide but not a bad thing to save $300/mo so I'm happy with it.

Or if they broken windows or an outside door that won’t lock.

The offer doesnt necessarily lock you in as @Alex Rodriguez mentioned, its  basically a foot in the door to negotiate, it lets the selling side know you are serious and looking to start a dialouge

Do you know if the crazy 100k to 200k over were cash buyers and wanted to lock in great deals?

School, Insurance, lock fees, MLS, etc...  

The rate I currently have locked in (also 15-year fixed) is 3.0%. 

Started to get hit up pretty aggressively recently for primary residence refinance deals - we are at 3.3% and locked in 2.5% through a reseller.

. :-)Imagine the awesomeness of buying during the downturn, hyperinflation occurring and your mortgage being locked in.