The assumption is not opposite of what the text states. The text on spell level says spell levels given a general indication of how powerful a spell is. Keyword general. By using the term general it means1) there will be specific cases that are outside the norm and 2) there are factors besides a spells level to determine how powerful the spell is such as the components required, the time to cast, and who has access to the spell, etc. The fact that HS is limited to who has it serves as a counterweight to the spell.
Yes. I do think rangers need to be buffed. Guilty as charged

That being said UA and additional rules including spells absolutely have been used to shore up a seen weakness of a class.
Be safe traveling during these times!