Imagine you are undertaking a web search for a specific item and you then click on a possible provider. Instead of instantly finding the information you are wanting about the product or service you are looking for, you simply arrive at a generic 'Welcome to...' homepage.
From there, you are now expected to navigate your own way to the part of the website currently of importance to you. This may be more difficult than it should be; and, often, you may simply give up, return to your original search, and try another option. In this way, companies can inadvertently lose business they never even knew they had the chance to gain!
Landing pages are geared to respond specifically to searches, instantly gaining the attention of the searcher. If you offer too many products or services to craft one for each, you can still indicate in the copy that key products are part of a range of choices, and then provide a link to the relevant content page.
REMINDER: Make sure all searchers have as easy a journey as possible to help them to find exactly what they're looking for