Jira Align Solution Layer ( Capabilities ) to have or NOT to have is the Question?

For organizations where the products and/or services are so complex that an Agile Release Train is not sufficient, the intent is to have a Solution Train. This is applicable for organizations in which multiple Agile Release Trains work together on one or more complex services and/or products.

Typically, the solution train is where hardware, software, and/or firmware form an integrated product.