Moisture = water, that cannot be up for debate even if everything else can. Most oils or butters used alone do not moisturise the hair, that is an incorrect use of the word, they do not increase or add to the water content of the hair (hydration).
Your hair might feel silkier, softer or more elastic, you might correctly describe the result as emollient
or at a push even conditioning
. Moisturising and conditioning are not one and the same, tho there is overlap. By contrast it might be correct to say an emollient rich product has moisturised your hair if it is increasing hydration.
It's like US citizens describing any supplement in pill format as a 'vitamin', just because your friends call it that does not mean it is and it is unhelpful to others to use the wrong term. Any health professional needs to know if you are really taking vitamins (A, B complex, C, E) or actually taking minerals, herbal remedies or essential fatty acids.
Just because words are used by people incorrectly doesn't change the meaning of a word, at best it adds a meaning (slang). The problem with slang is that it is not universal, it's specific to a friendship group, generation, culture, college, city, country. When we are talking science, albeit at an amateur level, and have newbies and different nationalities in the same conversation it's deeply unhelpful to accept erroneous definitions or slang for words like 'moisturise' and 'vitamins'. All that happens is that people get confused and misunderstand one another.