The other thing you fail to mention is that unless you sell your property your capital gains are made on paper only. Until you sell you cannot be sure that your property will make the gains that seem to be promised by the local market. And for most of us making a gain on paper is worthless as a paper gain cannot put food on the table. The theoretical capital gain is only worth anything to those who can leverage it to invest further to build their portfolio.
The other problem with the whole increase in house price by suburb thing mentioned in the article you quote is that it is based on actual house price sales by suburb. In many cases the number of houses sold in a suburb are really quite small - just 10 or 11 in some cases. When looking at such small numbers any gains could be more to do with the types of properties being sold one year compared with the types being sold in other years. When massive gains are seen it could simply be that the previous year all the houses sold were small houses on small blocks and this year the houses have been larger on larger blocks.
Just to go back to the original point about being near the sea being important for capital gains it is interesting that in the article you quoted although the top performing suburb is by the sea most of the rest of them are inland and none of the rest are by the beach.