There’s a reason we put our skincare in tubes (sugarcane) not jars. Skincare in jars encourage ingredients to oxidize (go rancid) faster because every time you open the lid of the jar you expose the cream to air and light. The product with oxidized ingredients may become less effective and may even become bad for your skin by generating free radicals. A jar also invites you to stick your fingers into it. No matter how clean you think your fingers are, there is always the risk of bacteria and other microbes entering the cream when you stick your fingers into it. You can use a spatula but these have to be carefully cleaned in between use to maintain hygiene. To prevent microbial build up, manufacturers often pile their products with chemical anti-bacterial agents and this would be completely unnecessary if they filled the creams in tubes instead of jars.