Conglomerates peaked in the US in the 1960s; since then, it's been believed that too much de-focus is bad. That said, it's certainly OK for a company to have multiple businesses. Berkshire-Hathaway is like an old-style conglomerate. GE is regarded as being very well run. Etc.

The danger of a conglomerate is that a culture or decision-making paradigm suitable for the dominant business(es) might not be good for others. E.g., smaller businesses might get ignored because they don't matter enough. Or they might not be allowed to move quickly and take risks. E.g., Xerox found that selling LISP machines and copier paper mixed badly, as reorders of the latter were held hostage to the immaturity of the former.