The necessity of recompilation with Lazarus when adding new packages/components is not touted as an advantage. It is a result of the IDE being truly cross-platform, and so not able to rely on Windows dll trickery to add component packages (.bpl-type packages) dynamically on-the-fly. What Delphi does with Windows .bpls cannot be done with Linux .so or Mac .dylib libraries transparently or effortlessly.
It is possible that some clever FPC/Lazarus developers will implement this in a cross-platform way in the future, but it is a hope, not a guarantee.
Although Delphi can now compile for a few non-Windows platforms, the IDE remains a Windows executable, and so is able to communicate with design and runtime packages dynamically.
However one advantage of the Lazarus approach is that you can recompile a new IDE and run the latest trunk version (surprisingly stable) in only a few seconds to get cutting edge functionality, without paying a cent, or waiting for a commercial release cycle for a new version. If Lazarus were a C++ compiler/IDE that took several minutes to recompile, this would clearly be a serious disadvantage, but with the Pascal recompilation time on modern machines being only a few seconds, the apparent disadvantage means little.