For a long time, especially on the previous blockchain, searching functions from the front ends were either inexistent or practically a joke for todays power of search engines.
But searching on the blockchain itself would be a nightmare for performance, that's why it's done on a database which has indexes for quickly accessing the relevant information that can be searched upon: account names, tags, titles AND content.
You might not be aware, but Google-like searching is already possible on Hive via the interface HiveSearcher, which has been created, developed and maintained by the Ecency team.
On the simple search page it is shown there are almost 100m "documents" indexed. Probably documents means posts, but it looks more mainstream this way.
The API of this tool is also used by the main general-purpose interfaces on Hive, Ecency (obviously), PeakD and hive.blog.
I know Leofinance is working on its own search system, which will be included initially on LeoMobile.
HiveSearcher is open source, but I think its services are paid depending on the amount of results serviced to those who integrate it. May be free up to a level, I don't know. I know PeakD, at the level of searches it has on their site, pays to use the API.
For a long time since it crushed Yahoo, Google was synonymous to search engine in almost the entire world. So we got used to the interface and the search parameters, even the advanced ones.
That's why HiveSearcher uses the same search parameters as Google.
You can search exact phrases using quotes, combine searches with AND/OR, excluding terms using minus, and use a number of filters which are specific to Hive (author, tags and more). Here's the official guide for HiveSearcher.
And something very important that one needs to keep in mind. Searches are made both in the title and in the content of the post, which is huge. Just like Google, but a huge step forward for Hive on the improved search capabilities. Furthermore, when using HiveSearcher you can choose to only search comments, when you select the type:comment filter.
HiveSearcher is still under development. For covering these costs and the server costs, there is a proposal on DHF. It is sometimes funded other times below the line. Maybe it counts that 