It’s fitting for limited crossover of job responsibility. What you are missing is the fact the tanks heal better than the healers in 99% of circumstances. The type of damage profile 14 has is much better suited to the tanks style of healing than it is for the healers healing. If you have reached a point where the tanks are healing can better than the healers you have taken a step too far
There is also the fact there is no limited crossover that allows any other role to effectively tank. It isn’t equitable crossover, it’s tanks doing everyone else’s job disguised as equitable crossover
The answer to that might be to up the damage or to nerf sustain, but only one of those options affects all content, the other only affects savage