There are plenty of business functions that support sales.
Marketing works to attract new customers, developers deliver solutions as promised, and customer support helps new buyers optimize their experience while using it. While the activities of those departments happen to benefit your most revenue-focused sector, nobody supports reps like sales enablement does.
It's not that other departments are neglecting their sales-supporting duties. It's that sales enablement teams are built with one goal: helping the sales team close deals as efficiently as possible.
Essentially, sales enablement works with sales operations to make it as easy as possible for reps to close new deals and maintain existing customer relationships. This can take many different forms, including providing relevant customer-facing information, offering training on sales techniques, and implementing helpful technologies. No matter what sales enablement looks like, its key function is to equip reps with everything they need to sell successfully.