Why Refill?
Our goal at usefull is to facilitate things to be "used in full". By providing a refill service, we're helping people reuse and reduce plastic.
Why are plastics so bad, anyway?

Plastic waste is toxic to animals and humans
The short answer is that plastics are made from petrochemicals (oil & natural gas) and always has other chemicals added to it (to make it stronger, more flexible, heat resistant, etc.), which are also toxic.
So when animals and humans ingest tiny pieces of plastic from food, water and the air, we're basically swallowing toxic chemicals. Scientists are studying the long-term effects of microplastics on living organisms, and early data suggests these microplastics can wreak havoc on organs and basic body functions like our metabolism.
And it's not just seafood where microplastics have been found, they've also been found in bottled water, beer, honey, sea salt, and more.
Moreover, plastic trash that drifts or is dumped into the ocean or waterways can obstruct habitat, hurt and strangle animals, and be confused for food.
What about recycling?

Recycling should be the last option, not the first
Recycling does not solve the plastic pollution problem because it is costly, takes a lot of resources and is very hard to do at mass scale. Here's why:
1) Plastic degrades every time it is recycled, therefore plastic can't be recycled more than 2 or 3 times
2) Recycling plastic is incredible costly (think of the collecting, sorting, cleaning, etc.) and it's also resource intensive
3) A lot of single-use plastic like straws or grocery bags are too small or thin to be recycled
4) It's more expensive to recycle plastic than to make new plastic from oil
This is why 91% of plastic in the world does NOT get recycled - that's billions of tons of plastic.
This is why it's so important to first and foremost, REDUCE virgin (or new) plastic, and REUSE the plastic things we already have. Remember, the sustainability mantra is refuse & reduce first, then reuse & repurpose, and recycle as a last resort.
How much difference can one person make?

Personal action matters
The photo on the left is my personal plastic toiletry trash for one year. Now multiply that by 30 to 35 years (time I may have left on this earth). By reusing these bottles through refilling, I can avoid adding over 500 plastic bottles into our ecosystem in my lifetime, just in my toiletry use.
One person may not save the earth, but that's not what it is asked of one person - what is asked is that each person do what they can to contribute to a healthier, more sustainable environment.
It clearly takes collective action, and collective action means MY actions, plus YOUR'S, plus OUR families', neighbors', friendss, and so on and so forth.
Don't underestimate the impact YOUR actions can make!
Sources (they're really good reads)
The world's plastic pollution crisis explained, National Geographic, Jun. 2019
A whooping 91% of plastic isn't recycled, National Geographic, Dec. 2018
There is plastic in your fish, Forbes, Jan. 2020
How big oil misled the public into believing plastic would be recycled, NPR, Sept. 2020