This is very basic stuff. You are overthinking it.
Microsoft is in the group of "big five" tech companies (Google, Amazon, Apple, Meta, and Microsoft). IBM is not in that group.
The reason for that is IBM is significantly smaller in terms of revenue and market cap and so on. IBM exists in a tier below the "big tech" level. This is how company sizes are measured.
Very simple. Not complicated.
Server operating systems are a small fraction of Microsoft's business.
Microsoft is in the group of "big five" tech companies (Google, Amazon, Apple, Meta, and Microsoft). IBM is not in that group.
The reason for that is IBM is significantly smaller in terms of revenue and market cap and so on. IBM exists in a tier below the "big tech" level. This is how company sizes are measured.
Very simple. Not complicated.
Server operating systems are a small fraction of Microsoft's business.