One of the most dangerous situations you create.
Two valves off, water heater kicks on and the T&P is clogged...
A pressure cooker that when it explodes, will kill and destroy your property.
Having the ENTIRE plumbing system to use as a buildup for when a supply line blows or forces a fill valve to malfunction, anything is better than containing that water heater expecting that $7 relief valve to open up when you need it most.
I've removed every hot side shutoff on every water heater I've replaced, no exceptions and I've warned every customer of the ones I've beared witness to.
Things can and will go wrong in plumbing and just because you know how your plumbing system operates, doesn't mean your wife, kids or the incoming new property owners know what kind of bomb you built in the basement.