Pretty much any on-prem software vendor is some mix of direct sales, partner sales, and through distribution. And in the case of, say, a product primarily for SMBs, the mix is probably going to tilt pretty heavily to partners. There's a lot of leverage to using partners and many of them will know and be connected to some market a lot better than you do.
There are differences with SaaS but they may not be as big as you think. For example, AWS mostly started as a go online with your credit card sale. Now? They have a big enterprise sales force and lots of partner relationships.
I bumped into a friend on the street a year ago he and told me about the business he had recently co-founded and taken through YC: https://www.ycombinator.com/companies/partnered. I told my co-founder about it and it became a significant part of his sales toolbox. I saw my friend last week and shared the single criticism my co-founder had. My friend told me they had recently been acquired by a competitor whose core functionality resolved our pain-point.
Strategic partnerships and white-labelling seem to be critical tools for growth in the current climate.
Whether or not there's any white-labeling involved, partnerships (VARs, SIs, now often public cloud providers, etc.) have been a key part of sales strategy for many types of products for decades.
There are differences with SaaS but they may not be as big as you think. For example, AWS mostly started as a go online with your credit card sale. Now? They have a big enterprise sales force and lots of partner relationships.