I will go much farther than Loraxchick on this subject. Professional betta breeders, the ones who make a living selling top quality stock, almost always keep that stock in jars that are 1 gallon or smaller. They do not do anything to impact the health or growth of their fish, it is after all their livelihood. To be blunt here, Betta splendens does not require anything much larger than maybe a 2 litre jar but few hobbyists will keep them in such small quarters. They also do not require individual heaters in their jars nor filters. The commercial breeders usually take care of chemical contaminants by doing water changes frequently, not by using a biofilter and they heat the jars by keeping them in a warm location. There is an enormous difference between hobby fish keepers like us and people that actual cater to a fish's minimal needs for good health and growth. The differences are a matter of personal taste, not necessity.
With all that said, my present 4 year old veiltail is in a 45 gallon tank that houses my endler breeding colony and some bristlenose plecs.
As far as the response you get on a Wiki site, there are no posts on a typical Wiki site that can be considered facts. At best they are akin to a blog by a rank amateur and at worst people believe their content and do all kinds of silly things with fish or other subjects. Here at TFF, the MODs try to correct misconceptions and prevent outright misinformation being spread unchallenged. Most Wiki locations don't even have that degree of checking answers. If you want facts, avoid Wiki sites except for one use they do have. sometimes they will give you some good key words for further searches that may turn up a well written and properly edited site.