in regards to PC capabilities; almost all business software, regardless of the platform, was text based so even a cheap monochrome XT clone would have worked perfectly fine. GUIs were good for beginners, but it would be some years before they were fast and practical enough to be a good a business solution. PCs were initially subpar when it came to gaming but they offered the best upgradability, raw CPU power (a 286 is roughly 50% faster than a 68000 at the same clock speed), peripherals, storage, keyboards, monitors, software compatibility, networking, serviceability, and access to locally sourced parts (meaning computers didn't need to be sent overseas for repairs). Thanks to rapidly dropping component prices they could cheaply upgraded and by 1990-1991 due to VGA's adoption, PCs started to become the premiere platform for next-gen games.

The problem with commodore's machines is that they were basically designed as consoles with keyboards. Even the Amiga was originally intended to be a console before it was redesigned as a true computer. The issue is that the consoles can get away with releasing entirely new systems every 3-5 years due to having lower initial costs (typically under $100 in the 80s) where as commodore's computers were just too expensive to do that. As result C64 owners stuck with the system long after the amiga was released because upgrading to new commodore computer was so expensive. Apple computers suffered from a similar design problem but because their niche in the 80s and 90s was education and desktop publishing rather than gaming, there was less need for them to be pushing hardware boundaries. That's why 80s era Macs were still being used in schools and libraries even in the early 2000s.

So in the end it was easier for most families to buy a console for the kids and a cheap PC for general use rather than invest in a single commodore computer with limited upgradability. That's why PCs and consoles dominated sales.

IBMs machines were not as expensive as people think. They were not that much different in price from similar Commodore desktop systems while XT and AT clones were by far the cheapest disk-based desktop form-factor computers in the 80s. Even Commodore themselves sold PC clones at lower prices than their Amigas. While it was possible to make make all-in-one form factor wedge computers, the integrated keyboards, limited upgradability and storage options made these unsuitable for business use. For example this advertisement from a 1989 issue of Byte magazine gives a good comparison of prices at the time.

link: PC, Apple, and Commodore advertisement from 1989

In 1989 a Amiga 2000 was $1429 or $1999 with a 20mb HDD compared to $1579 for an 8086 PS/II model 30 with a 20mb HDD or $1829 for the 286 model. So a little more expensive but a smaller difference that most people realise. On the same page we can also see than AST 286 clones for $799 or $1049 with a hard drive. Just a year later it was possible to purchase a 286-16 with VGA for $489 or $1079 with a 40mb HDD and VGA monitor. Keep in mind that while an amiga 500 with a monitor and a 20mb hard drive at the time would have cost close to $1400.

link: 286 and 386 clones from 1990

Even if we go back to 1986; PC clones were still the cheapest desktop form factor machines with clone turbo XTs starting under $400 and clone 286s from $995. By comparison at that time the standard retail price for a C64 was $199 plus $50 for the datacorder or $200-220 for a 1541 disk drive and a C128 with a 1571 was around $550. So even back PC clones would have the cheapest viable business option.

link: XT and 286 clone from 1986