Why is Shiny a dependency of devtools? : <p>When I install devtools, I get shiny as a dependency. </p>

<pre><code>&gt; install.packages("devtools")
Installing package into ‘/Users/xxx/tmp/xxx/packrat/lib/x86_64-apple-darwin15.6.0/3.5.3’
(as ‘lib’ is unspecified)
also installing the dependencies ‘zeallot’, ‘colorspace’, ‘utf8’, ‘vctrs’,
 ‘plyr’, ‘labeling’, ‘munsell’, ‘RColorBrewer’, ‘fansi’, ‘pillar’,
 ‘pkgconfig’, ‘httpuv’, ‘xtable’, ‘sourcetools’, ‘fastmap’, ‘gtable’,
 ‘reshape2’, ‘scales’, ‘tibble’, ‘viridisLite’, ‘sys’, ‘ini’, ‘backports’,
 ‘ps’, ‘lazyeval’, ‘shiny’, ‘ggplot2’, ‘later’, ‘askpass’, ‘clipr’,
 ‘clisymbols’, ‘curl’, ‘fs’, ‘gh’, ‘purrr’, ‘rprojroot’, ‘whisker’, ‘yaml’,
 ‘processx’, ‘R6’, ‘assertthat’, ‘rex’, ‘htmltools’, ‘htmlwidgets’, 
 ‘magrittr’, ‘crosstalk’, ‘promises’, ‘mime’, ‘openssl’, ‘prettyunits’,
 ‘xopen’, ‘brew’, ‘commonmark’, ‘Rcpp’, ‘stringi’, ‘stringr’, ‘xml2’,
 ‘evaluate’, ‘praise’, ‘usethis’, ‘callr’, ‘cli’, ‘covr’, ‘crayon’, ‘desc’,
 ‘digest’, ‘DT’, ‘ellipsis’, ‘glue’, ‘git2r’, ‘httr’, ‘jsonlite’,
 ‘memoise’, ‘pkgbuild’, ‘pkgload’, ‘rcmdcheck’, ‘remotes’, ‘rlang’,
 ‘roxygen2’, ‘rstudioapi’, ‘rversions’, ‘sessioninfo’, ‘testthat’, ‘withr’
</code></pre>

<p>How does this make any sense? Is this expected, and if yes, how can I prevent it from happening? I am using R 3.5.3 with 0-Cloud mirror.</p>
