Great question — answering as the UphillTech team:
Not a good idea. For the following reasons: This page will not provide good answer for either topic. This page will be optimized for 2 completely different topics and to rank it you'll have to add some content related to each topic thus confusing the SE. The reason you see main pages at the top for these queries is because these are very competitive keywords. And still there are only 3 main pages in top 10 for "web design" https://i.sstatic.net/vyt0y.jpg Forget about ranking our pages for top keywords and start with a long tail, there's plenty of traffic in the long tail for these niches: https://i.sstatic.net/vyt0y.jpg
Full answer by Igor Gorbenko: https://webmasters.stackexchange.com/a/107438 (CC BY-SA 3.0).
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