There are plenty of old-school businesses that do just fine with minimal online presense.
That said, this mostly includes baby boomers and gen X, and the modern workforce is actively moving to millennials and even generation Z employees who live and breathe the Internet and base their buying decisions on online reviews and social media.
They also use Facebook or Twitter as customer support or presales channels.
Depending on your target market (buyer persona), social media may be your go-to choice. It’s a long-term play and works really well primarily for product-driven businesses, low-cost ones and those easy to purchase and sign-up for with limited friction.
This means B2C (business to consumer) channels or more affordable services.
Top brands selling expensive product or services also use social media. But it’s an expected brand building tool for them. Businesses in the higher tier are conducted with sales and business development, marketing plays a supportive role for reputation building and credibility, along with building an audience or nurturing leads over time.