The hardware Bachus mentions are still basic Midi controllers and very primitive compared to even a cheap arranger (£50 Casio) in what they can do, it’s the software and external computer that makes them great.

Virtually all arranger players (99.9% of which are home hobby players) are not interested in having to do any work to sound great, but instead just want to press a button and have everything done for them. (Hence manufactures make arrangers, as they are easy play instruments (Sound great without the wait)

Ask most arranger players and they are amazed by the sound of VSTs out there; however mention that they have to do a little work to get them to sound as they want and all interest is lost. (They go straight back to the more limited hardware boards)

Manufactures only build what they can sell, and most arranger players want hardware, not software based boards. (Even though the arrangers they play are just bespoke software/hardware combinations)

Bill