Arc System Works has a long tradition of making quality fighting games. Dragon Ball has a tradition of big selling games.
So all ASW needs is a huge anime IP and a big publisher backing them to be a great success. Sony (+ their partner Kadokawa) has access to a ton of top anime IPs they are interested to use in game and also to promote Sony's anime streaming services and anime. Sony stated collaborations between Sony divisions as one of their top short term priorities in a recent IR report.
Sony wants to expand on PC and Asia. ASW is making the fighting game of the game the made the biggest amount of money worldwide during the last decade, which is huge ass Korean F2P beat'em up MMO, which has been super huge in Asia for more than a decade. This game and the fighting game of League of Legends -being made by the former EVO owners, who are now also working with Sony overviewing the new EVO- will make the fighting genre grow and more than double its size if a small portion of the LoL and Dungeon Fighter fanbases get interested on their fighting games.
On top of that eSports are growing and becoming huge, and the most console centric genre is fighting games. Sony wanted to keep this genre under their umbrella by getting many 3rd party fighting games exclusives, buying EVO partnering with the UFC guys and patenting eSports related stuff like bets, making/funding tournaments, etc. But it's too rare to see them making all this efforts for games by other people, so would make sense to milk it themselves with their own fighting games, so they need to buy someone/some IP to have their own fighting game like Nintendo or MS has.
So yes, ASW would help them to grow directly and indirectly by banking their available top anime IPs, popularizing these IPs and the Sony's anime streaming services where they are, by making more money than a Kojima game with a small team (which in addition to work in that game also works in 2 or 3 more), reaching non very console friendly Asian markets like Korea and China thanks to the Dungeon Fighter IP, to make a huge growth on PC, to keep better positioned on eSports with their own games (as happens with GT in racing) etc.
The fighting game genre is better than it ever has been, with most of their top IPs performing great during this PS4+Switch generation:
- Smash Ultimate is the best selling game on its series with 23 million copies and counting
- MKX is the best selling MK ever (11 millions), and MK11 is on track to outsell it (~9 million)
- SFV is close to outsell SF2 and if we add the SFV DLC then if must pass it by a fair margin
- SFIV was also successful to the point it caused a second golden era in the genre that was pretty much dead outside a few exceptions, but Capcom needed money for SFV because of Capcom's financial issues back then (not due to SFIV, but due to other games and failed project), in the same way they needed MS money for Dead Rising or Nintendo's money for MH. Since then Capcom had many very successful games, so won't need Sony's money and SFVI is planned to be multiplatform and crossgen.
- Tekken 7 has sold over 7 million copies and is on track to outsell the biggest selling Tekken ever (Tekken 3, 8 million)
- Dragon Ball FighterZ is Arc System Work's best selling game with over 6 million copies
- Guilty Gear Strive just debuted with the biggest ASW launch sales ever
- All these mentioined games feature a ton of DLC and IAP split on seasons, which means they are generating way more money than previous entries on their series, that didn't feature DLC/IAP
- The two biggest and top grossing PC worldwide (League of Legends and Dungeon Fighter) will have a fighting game in the coming years, if only a small portion of their hundreds of millions of fans get interested on the fighting games the genre will grow a lot
- eSports viewship is growing a lot and the figthing genre is probably the most console centric eSports genre, so it's a strategic opportunity for people like Sony so this is why invest on it.
Turns out that the Dungeon Fighter fighting game is being developed by Arc System Works, who also generated more money than any Hideo Kojima game but with a small team while also working on 2 or 3 games more in a games using a top anime IP, so Sony can ask them to do the same with other top anime IPs and use it to bank themselves all the fighting game + eSports effors they have been making.
In addition to profit from it directly, they also would get indirect profit by making their anime IP/anime streaming services more popular, and to grow in the PC market, specially in those Asian countries where consoles aren't so big like Korea or China.
On top of that, Bandai Namco didn't make huge efforts regarding eSports with DBZ, but it generated interest specially in key PlayStation markets like France, UK and Spain, and Strive now getting a great netcode opens the door to increase the online tournaments.
Sony also downsized their Japan Studio, so they may want to buy some Japanese studio to compensate the amount of Japanese exclusives.
So for Sony not only makes sense to buy a fighting game studio, makes more sense to buy Arc System Works than Netherrealm because in addition to be cheaper and more profitable, it would make more sense becaue it also helps them strategically both inside and outside gaming.