IMO-(In my opinion) on forms like these most (not all) posters are new in the hobby and are seeking advice and the more experienced hobbyist give advice based on their opinion and personal experience. Some are more passionate than others on what they feel is best husbandry practiced for this species. I have only been here a short time and most of the advice is spot on IMO, maybe not what I would do..but the advice is not wrong IMO.....just their way of doing things that work for them.
One thing I try to do when giving advice is to explain why something needs to be done to give the one asking for help information so that they may learn and find what works for them in their setting. As stated by DQ- "what works for one may not work for another".
IMO as an experienced fish keeper (over 30 years) and breeding this species (Betta splendens) for the past 11 years, my main goal in giving advice is to help the poster to be successful and to stay in this hobby and promote responsible fish keeping.
IMO you have people that "have" fish and those that "keep" fish...a big difference IMO as anybody can have a fish but it takes work and dedication to be a true keeper and hobbyist.
IMO a keeper and hobbyist can be of any age, we all had to start at one point and we all make mistake, the keeper will learn from these mistakes and improve their fish keeping, they will research, listen, learn and improve on their skills with time and experience.
IMO- there is a big difference in a fish that survives-vs-thrives, just because you can doesn't mean you should when it come to responsible fish keeping.
As a responsible hobbyist I want my hobby and the people in this hobby to be successful and giving a new hobbyist the tools for success is important IMO.
I do agree that for the more experienced hobbyist you can successfully keep this species in half gallon tank or less, but as experienced hobbyist we know how important water changes and proper feeding are, often the new hobbyist will not have a full understanding of this or even know how to make water changes...that is why they are here....
They want to know how to properly care for their fish and we the experienced hobbyist need to guide them in the right direction so they can be successful and IMO when the new hobbyist report that they have a half gallon tank we as responsible experienced hobbyist need to guide them to a larger tank to improve their chances of success until they gain a bit more experience and understanding of the importance of water quality and husbandry practice.
There are hundreds of ways to keep fish that thrive in our closed ecosystems we call an "Aquarium" it is finding what works for our systems, fish, source water and the amount of time, money and work we are willing to put into it for healthy-thriving-happy-fish and aquariums........
This is just my opinion...............