This causes the tree to be deformed at that point and send out many limbs and the central trunk basically stops growing. 

Does glued down vinyl hold up better if there is a water spill or a leak or will it lift and bubble or deform from water?

Look for deforming shingles, if many of them are starting to fishmouth, meaning they are rising in the middle of their edge that can be a sign of age.3.

"These people have no hope of again dying,And so deformed has their blind life becomeThat they must envy every other fate."

Their dog which is allowed under the lease has clawed the inside garage door that leads into the house, the wood for the door stop is deformed and needs to be replaced.3.

My thoughts on that are since it's part of the fitting (it's between the flange and the bottom of the bowl),  it may remain sealed or reseal itself in a scenario where once the wax gasket is deformed for whatever reason the resulting leak is permanent until you replace the wax gasket.Again, experience over time will prove it's suitability for the application.

If it dried without deforming, it will be fine.HOWEVER...If you have to patch anyway, and especially if you are paying someone to patch anyway, it will cost essentially nothing to remove and replace it.  

Plus Home Depot has great prices on their Pro Pack bundles of the stuff.One word of caution though, be careful about using MDF on any hard surface flooring that is likely to be exposed to water (i.e. bathrooms) or mopped regularly (i.e. kitchens) as they can soak up water and get a little swollen/deformed. 

How they deform and get really thin at the top?

The soil freezes, expands, and causes the same type of deformation as a settlement issue.