Nobody buys a patio from a description. They buy it from a photograph of a patio that looks like the one they have been imagining, ideally on a property that resembles theirs.
So the portfolio is not decoration, it is the sales material: before and after, from the same angle, in decent light, with a line about what the problem was. Drainage that was solved, a slope that was terraced, a lawn that was failing. That is more persuasive than any adjective.
This is also the trade where social media marketing genuinely earns its place, because the work photographs well and neighbours are the audience. It is still proof rather than a lead source — online reviews versus word of mouth covers how the two combine.