DynamoDB and ScyllaDB are very different use cases than Spanner.
• Spanner is more in the domain of CockroachDB — distributed strong consistency and ACID compliance. Both are ANSI SQL.
• DynamoDB and ScyllaDB are in the NoSQL key-value store / wide column domain. ScyllaDB is API compatible with DynamoDB, but is also API compatible with Cassandra Query Language (CQL). These databases are for eventual consistency use cases.
As to the "99%" comment, there are over 415 databases currently tracked on DB-engines.com (https://db-engines.com/en/ranking). It is a very competitive and specialized industry. Very few databases have more than 1% marketshare these days.
According to this: https://6sense.com/tech/relational-databases
...only the top 9 options show >1% of marketshare.
MySQL being so far in the lead (42%) is far more likely due to it being baked into so many OEM deals (over 2,000 as per https://www.mysql.com/oem/). Like, every WordPress site in the world than anything else.
Yet that doesn't really make MySQL great for every use cases. It has obvious limitations.
We also have to note that different studies have far different results.
In this video: https://statisticsanddata.org/data/the-most-popular-database...
It shows a different set of top databases, and has 11 of them showing >2% of marketshare. It has MySQL at only 13.91% of marketshare, with Oracle being on top at 31.19%.
The source of this poll is TOPDB Top Database index:
https://pypl.github.io/DB.html
It's not based on money marketshare, nor on poll results, but simply is counting how often a database is searched on Google. Note that anything that could garner 1% of the market would suddenly catapult that database into the top 16th place on the list.
At the end of the day, database "market share" — however it is calculated — is not representative of exclusive percentages. Many companies run more than 1 type of database. There might even be multiple SQL and NoSQL databases, each designed for purpose, at large enterprises. OLTP, OLAP. I would not be surprisedi in the least to learn that large corporations had well over 100 different databases running at any given time.
So, back to your basic comment: if a database is useful for even 1% of the use cases, that would still place it in the top 20 databases in the industry.
Moreover, a lowest-common denominator database will not be able to support many critical use cases where you really do need a specialized data model, or index type, or query language, or workload type, or latency, or distribution, or scale of QPS/TPS/OPS, or total data size or query payload size, etc.
I have likened the database industry to the state of Christianity after the Reformation. Even if there are still plenty of "Catholics" (classic SQL adherent, like Oracle), there are also Reformed faiths ("NewSQL" / "Distributed SQL", e.g., PostgreSQL), plus any number of Protestant reformation alternatives (NoSQL). I'm not sure what the "Orthodox" in this analogy refers to. Maybe SQL data warehouses? The schism between OLTP and OLAP? Dunno.
Anyway, it's an analogy. Bound to break down at some point.
At the end of the day, my advice: use the database most closely aligned to the dataset and workload and use case you have at hand. Don't just throw something at a problem because it's a popular choice, or because it's the database you happen to be most familiar with.