In most cases, having commands echo to the console was harmless, and helped provide a form of progress indicator for whatever task the batch file was performing. The only times that such echo would be problematic would be when the batch file was trying to format a screen layout for itself. Having a screen look like:
A>echo Please type one of the following commands:
Please type one of the following commands:
A>echo WOOZLE -- Run the Woozle program
WOOZLE -- Run the Woozle program
A>echo FNORBLE -- Do an inventory of the Fnorbles on your system
FNORBLE -- Do an inventory of the Fnorbles on your system
Although a batch file could include messages within a batch file preceded by REM and output them with echo on, some people might have their prompt set to something that's rather long, or even has multiple lines, and trying to predict how to format things meaningfully could be difficult.
In short, having echo on by default wasn't objectionable. In fact, until the introduction of DOS 3.0 it wasn't possible to suppress the display of the first command in a batch file, so the execution of batch files that were supposed to display messages would often start with something like
A>ECHO OFF, but that wasn't a particular problem.
Note that while there are some kinds of batch files that routinely start with
@echo off, there were many users who ran their own batch files much more often than those from externally-produced software, and would seldom have reason to disable echo.