What Are The Disadvantages Of Advertisement Through Websites?

Some of the disadvantages of advertisement through Websites includes:
Advertisements on websites requires users to visit the link and can consume people's time which can make those advertisements unexplored by reader,
Advertisements on websites requires Internet, which requires reader to first connect to Internet and thus might not be able to target large masses who are in no mood of using Internet or want information more hassle free,
Internet is not available in so many areas and high speed Internet is usually expensive to be afforded in poor and third world countries, thus keeping many customers away.
Website advertisements, If not of large size, might get unnoticed by readers.
Since Internet is not regularly used by many potential spenders, website advertisements will fail to cater to them.