That ship sailed a long time ago.
It was normal back in the 1990s for InfoSec folk to assume that "if it's connected to the Internet, eventually, it will be compromised."
The goal (then, as now) is to implement layered (defense-in-depth) mechanisms to deter such activities -- at perimeters, network and systems infrastructure platforms and software implementation.
This is (and has been for a long time), a well-defined, although usually poorly (if at all) implemented set of processes and procedures.
The levels of complexity for Internet resources have vastly increased over the past 25 years. Info Security techniques have advanced as well, but again are often poorly or not at all implemented.
However, far too many organizations implement a "Skittles" type defensive posture rather than defense-in-depth posture.
There are a variety of reasons for this:
1. Those responsible are ignorant of good security practice;
2. Those responsible are aware of the risks, but ignore it as it negatively impacts profit;
3. Those responsible are aware of the risks, but implement inadequate defenses because of the impact on time-to-market and/or profit.
4. But the most egregious offenders are software developers, who often just bolt on weak security measures or just ignore security altogether, rather than design with security as a primary consideration.
There are other reasons, but those are the big ones, IMHO.